Elements of Mechatronics System

Mechatronics Questions and

Answers

Prepared by : Jack E. Bagbaga

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Elements of Mechatronics
System”.

1. Where and when was the word Mechatronics invented?

a) Japan(1960)
b) Japan(1980)
c) Europe(1960)
d) Europe(1980)

Answer: a
Explanation: The word Mechatronics was first used in Japan in the late 1960s, spread through Europe and now
commonly used in all other parts of the world. In the 1980s there was a veritable explosion in Microprocessor
based products.

2. A servo motor is a typical example of _____

a) Electronics system
b) Mechanical system
c) Computer system
d) Mechatronics system

Answer: d
Explanation: A servo motor is a typical example of a mechatronics system. It is a motor with sensory feedback and
it is used for obtaining very complex and precise motions.

3. What is the function of an input signal conditioning unit?

a) To produce control signals
b) To amplify the signal and convert it into digital form
c) To perform mechanical work
d) To produce electrical signals

Answer: b
Explanation: Input signal conditioning devices amplify the signals, converts them into digital form, and supplies the
conditioned input signals to digital control. Control signals are produced by digital control. Mechanical actuators
perform mechanical work. Electrical signals are produced by input sensors.

4. The main mechanical components of a servo motor are stator and rotor.
a) True
b) False

Answer: a
Explanation: The main mechanical components of a servo motor are stator and rotor. The electrical components
consist of field windings and rotor windings, circuitry for power transmission.

5. The main function of Actuator is _____

a) To produce motion
b) Detect input
c) Detect output
d) Detect the state of the system

Answer: a
Explanation: The Actuators produce motion and cause some actions whereas sensors detect the state of system
parameters, inputs and outputs.

6. Example of ‘Stand-alonesystem’ is _____

a) Machining centres
b) Washing machine
c) Robots for parts handling
d) Automated inspection stations

Answer: b
Explanation: The example of a stand-alone system is the washing machine. Machining centres, robots for parts
handling and automated inspection system are large factory systems.

7. Which among the following carry out the overall control of a system?
a) Graphical display
b) Sensors
c) Actuators
d) Digital controls

Answer: d
Explanation: The overall control of the system is carried out by digital controls. Graphical display provides visual
feedback. The actuators produce motion and cause some actions whereas sensors detect the state of system
parameters,inputs and outputs.

8. A humanoid robot is an example of _____

a) Artificial intelligence
b) Stand-alone systems
c) Large factory systems
d) High level distributed sensor microcontroller actuator

Answer: a
Explanation: Humanoid robot is an example of a system that incorporates intelligent control or artificial intelligence.
The example of a Stand-alone system is washing machine whereas wire aircraft and automated inspection stations
are examples of high level distributed sensor and large factory systems respectively.

9. Where is the feedback generated by sensors in a mechatronics system given?

a) Input sensors
b) Comparators
c) Mechanical actuators
d) Output sensors

Answer: b
Explanation: The feedback signal is given to comparator, which compares the desired input signal to the feedback
signal to produce an error signal. Input sensor detects the input signal. Output sensors produce the output.
10. A Mechatronics system contains feedback.
a) True
b) False

Answer: a
Explanation: Feedback signals are generated by sensors of mechatronics system, given to comparators to produce
the error signal if any.

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Types of Transducers”.

1. What are transducers?

a) They convert power from one form to another
b) They convert work from one form to another
c) They convert work to power
d) They convert energy from one form to another

Answer: d
Explanation: Transducer are devices that convert energy from one form to another. This energy can be either
mechanical energy, light energy, heat energy or any other forms of energy.

2. Active transducer do not require any type of additional power source for an operation.
a) True
b) False

Answer: a
Explanation: Active transducers do not require any additional power source for converting the energy from one form
to another as they work on the principle of energy conversion. One such example of active transducer is
thermocouple.

3. What type of energy conversion does a piezoelectric transducer perform?

a) It converts mechanical energy to sound energy
b) It converts sound energy to mechanical energy
c) It converts mechanical energy to electrical energy
d) It converts electrical energy to mechanical energy

Answer: c
Explanation: A piezoelectric transducer converts mechanical energy to electrical energy. They are generally used to
detect a knock or any impulsive force. They are also used in electronic drum pads to detect the impulse provided by
the drumsticks.
4. Pirani Gauge is an example of which type of transducer?
a) Pressure transducer
b) Temperature transducer
c) Light transducer
d) Mechanical transducer

Answer: a
Explanation: Pirani Gauge is a pressure transducer. It’s a thermal conductivity gauge used to detect pressure in
vacuum conditions. It was named after a German physicist “Marcello Stefano Pirani” who invented it in 1906.

5. The IC LM35 is used as which type of sensor?

a) Pressure sensor
b) Temperature sensor
c) Light sensor
d) Mechanical sensor

Answer: b
Explanation: The LM35 IC manufactured by Texas Instruments is used as a temperature sensor. The output
voltage generated by this IC is linearly proportional to the temperature in Centigrade. The output voltage is
directly proportional to the temperature.

6. What is the range of frequency of the waves produced by the Ultrasonic transducer?
a) 20 Kilohertz to several Gigahertz
b) 1 Kilohertz to several Gigahertz
c) 40 Kilohertz to several Megahertz
d) less than 20 Kilohertz

Answer: a
Explanation: Ultrasonic transducers produce frequency ranging from 20 Kilohertz to several Gigahertz. Ultrasounds
have a wide range of application in many fields, but majorly they are used for measuring the distance of objects.

7. What is the full form of LVDT with respect to displacement transducer?

a) Linear variable differential temperature
b) Linear variable differential transformer
c) Liquid visible differential transformer
d) Liquified visible differential transformer

Answer: b
Explanation: LVDT stands for Linear variable differential transformer. It is a displacement transducer that
converts rectilinear motion to electric signals. They are used widely due to their robustness.

8. What is the effect on properties of LDR when light falls on it?

a) Its resistance remains same
b) Its resistance changes
c) Its capacitance changes
d) Its inductance changes

Answer: b
Explanation: When light falls on LDR (Light dependant resistor) its resistance changes. It is inversely proportional
to the intensity of light. When light falls on LDR, the resistance decreases and more current starts to flow
through it. It is used to measure the intensity of light.

9. What is measured by a hall effect transducer?

a) Electric flux
b) Electric Field
c) Magnetic field
d) Temperature

Answer: c
Explanation: Hall effect transducers or Hall effect sensor is used for measuring the magnitude of the magnetic
field. The output voltage produced by the sensor is directly proportional to the strength of the magnetic field
passing through it.

10. In which state of chemical substances does a chemical sensing device work?
a) Solid
b) Liquid
c) Vapour
d) Plasma

Answer: c
Explanation: The chemical sensors detect the chemicals in the vapour form. Most of the chemical sensor are in the
form of gas sensors. These sensors are widely used in industries to detect any gas leakage or for automatic fire
alarms.

1. What is the relative error percentage of an observation taken by an ultrasonic sensor which predicts the
distance of an object to be 2.12cm but the actual value is 2cm?
a) 12%
b) 10%
c) 6%
d) 1%

Answer: c
Explanation: Given: Actual Value=2cm
Measured Value=2.12cm
Absolute error=Measured Value-Actual Value
Absolute error=2.12cm-2cm=>0.12cm
Relative error=(Absolute error/Actual Value)*100
Relative error=6%

2. What is the relative accuracy ratio of an observation taken by a distance measuring sensor which predicts the
distance of an object to be 7.19cm but the actual distance is 7.02cm?
a) 13:719
b) 17:619
c) 17:702
d) 13:619

Answer: c
Explanation: Given: Actual Value=7.02cm
Measured Value=7.19cm
Absolute error=Measured Value-Actual Value
Absolute error=7.19cm-7.02cm=0.17cm
Relative accuracy=(Absolute error/Actual distance)
Relative accuracy=(0.17/7.02)=>17:702

3. What is the mean value of a distance observation set taken by a distance measurement sensor?
Observations={2,2.13,2.1,1.9}
a) 2.0325
b) 2.2
c) 2.125
d) 2

Answer: a
Explanation: Given: Observation set={2,2.13,2.1,1.9}
Mean=Sum of observations/Total number of observations
Mean=(2+2.13+2.1+1.9)/4
Mean=2.0325

4. Static characteristic of a sensor cannot be found using calibration.

a) True
b) False

Answer: b
Explanation: Static characteristic of a sensor can be found using calibration. Calibration refers to a comparison
between a known or standard measurement to the unknown measurement taken by the tool which has to be
calibrated.

5. What is the relative accuracy ratio of an observation taken by a IR(Infrared) sensor which predicts the
distance of an object to be 1.26 cm but the actual distance is 1cm?
a) 13:409
b) 13:50
c) 17:719
d) 13:619

Answer: b
Explanation: Given: Actual Value=1cm
Measured Value=1.26cm
Absolute error=Measured Value-Actual Value
Absolute error=1.26cm-1cm=>0.26cm
Relative accuracy=(Absolute error/Actual distance)
Relative accuracy=(0.26/1)=>13:50

6. Static characteristics of any sensor or transducer are determined by observing criteria’s that vary very slowly
with time.
a) True
b) False

Answer: a
Explanation: Static characteristics of any sensor or transducer are determined by observing criteria’s that vary
very slowly with time. Dynamic characteristics of any sensor or transducer are determined by observing criteria’s
that vary rapidly with time.

7. Accuracy and precession are same for a sensor’s observation.

a) True
b) False

Answer: b
Explanation: Accuracy and precession are not same for a sensor’s observation. Accuracy is the observation closest to
the true value whereas precession is the closeness of a observation among the predefined sets of observations.

8. Hysteresis error of any sensor has maximum difference between the observed value and actual value.
a) True
b) False

Answer: a
Explanation: Hysteresis error of any sensor has maximum difference between the observed value and actual value.
Inside the specified range of the sensor, it is the maximum deviated observation from the actual observation.

9. What is the relative accuracy ratio of an observation taken by a IR(Infrared) sensor which predicts the
distance of an object to be 4.16cm but the actual distance is 4.09cm?
a) 7:409
b) 13:603
c) 17:719
d) 13:619

Answer: a
Explanation: Given: Actual Value=4.09cm
Measured Value=4.16cm
Absolute error=Measured Value-Actual Value
Absolute error=4.16cm-4.09cm=>0.07cm
Relative accuracy=(Absolute error/Actual distance)
Relative accuracy=(0.07/4.09)=>7:409

10. What is the relative error percentage of an observation taken by a distance measuring sensor which predicts
the distance of an object to be 2.32cm but the actual value is 2cm?
a) 12%
b) 7.09%
c) 6%
d) 16%

Answer: d
Explanation: Given: Actual Value=2cm
Measured Value=2.32cm
Absolute error=Measured Value-Actual Value
Absolute error=2.32cm-2cm=>0.32cm
Relative error=(Absolute error/Actual Value)*100
Relative error=16%

11. What is the average value of a distance observation set taken by a ultrasonic sensor?
Observations={5,5.413,5.41,4.97}
a) 5.0325
b) 5.198
c) 5.125
d) 5.07325

Answer: b
Explanation: Given: Observation set={5,5.413,5.41,4.97}
Mean=Sum of observations/Total number of observations
Mean=(5+5.413+5.41+4.97)/4
Mean=5.198

12. Static characteristics are related to the steady state response of an instrument.
a) True
b) False

Answer: a
Explanation: Static characteristics are related to the steady state response of an instrument. Steady state
response of sensor is the relationship between input and output when the output changes very slowly or remains
constant after a span of time. And static characteristics are the characteristics that changes very slowly or
remains constant.

13. What is the mean value of a distance observation set taken by a distance measurement sensor?
Observations={3,3.213,3.11,2.97}
a) 3.0325
b) 3.2
c) 3.125
d) 3.07325

Answer: d
Explanation: Given: Observation set={3,3.213,3.11,2.97}
Mean=Sum of observations/Total number of observations
Mean=(3+3.213+3.11+2.97)/4
Mean=3.07325

14. What is the relative accuracy ratio of an observation taken by a distance measuring sensor which predicts the
distance of an object to be 6.16cm but the actual distance is 6.03cm?
a) 13:719
b) 13:603
c) 17:719
d) 13:619

Answer: b
Explanation: Given: Actual Value=6.03 cm
Measured Value=6.16 cm
Absolute error=Measured Value-Actual Value
Absolute error=6.16cm-6.03cm=>0.13cm
Relative accuracy=(Absolute error/Actual distance)
Relative accuracy=(0.13/6.03)=>13:603

15. What is the relative error percentage of an observation taken by an infrared sensor which predicts the distance
of an object to be 3.32cm but the actual value is 3.1cm?
a) 12%
b) 7.09%
c) 6%
d) 1%

Answer: b
Explanation: Given: Actual Value=3.1cm
Measured Value=3.32cm
Absolute error=Measured Value-Actual Value
Absolute error=3.32cm-3.1cm=>0.22cm
Relative error=(Absolute error/Actual Value)*100
Relative error=7.09%

1. Which error is also termed as measurement error?

a) Static errors
b) Dynamic errors
c) Systematic errors
d) Statical error
Answer: b
Explanation: Dynamic error is also termed as measurement error under specified conditions. Dynamic error is defined
as the difference between the actual or true value with a quantity that changes with time.

2. In retardation type measuring lag the instrument responds after an unspecified dead time lag.
a) True
b) False

Answer: b
Explanation: In retardation type measuring lag the instrument does not responds after an unspecified dead time
lag. The instruments respond immediately as soon as a change in measured quantity is encountered.

3. Active transducers do not require power source for operation.

a) True
b) False

Answer: a
Explanation: Active transducers do not require power source for operation. These types of transducers convert one
form of energy to another without any external power source. Example:- Photovoltaic cells present in solar panels.

4. Which among the following transducer is an example of active transducer?

a) LDR (Light dependant sensor)
b) Strain gauge
c) Hall effect sensor
d) Photovoltaic cell

5. Which among the following transducer is an example of passive transducer?

a) Chemical transducer
b) Thermoelectric transducer
c) Strain gauge
d) Piezoelectric transducer

Answer: c
Explanation: Strain gauge is an example of passive transducer. Passive transducers are those types of transducers
that bring change in passive electrical quantity usually with the help of external power source. Strain gauge is a
device that changes its resistance when there is change in applied pressure.

6. Fidelity is a static characteristic.

a) True
b) False

Answer: b
Explanation: Fidelity is not a static characteristic. It is a dynamic characteristic of an instrument. Fidelity refers
to the degree of exactness of a measured value with a measured quantity that has been measured without
dynamic errors.
7. Measuring lag is a dynamic characteristic.
a) True
b) False

Answer: a
Explanation: Measuring lag is a dynamic characteristic. Sensors, transducers or any instrument do not respond
immediately to the change in input. Measuring lag refers delay in response of an instrument to the change in input.

8. In time delay type measuring lag the instrument responds immediately as soon as the input is altered.
a) True
b) False

Answer: b
Explanation: In time delay type measuring lag the instrument does not responds immediately as soon as the input is
altered. In this type of time delay type measuring lag the instrument responds after an unspecified dead time lag.

9. Which instrument can be used to measure time without any errors?

a) Analog Clock
b) Digital Clock
c) Atomic clock
d) Doomsday clock
Answer: c
Explanation: Atomic clock is an instrument can be used to measure time without any static errors. These are the
most accurate instrument that can accurately measure time and frequency and are used as standard for different
purpose such as for global navigation satellite systems.

10. Which method can reduce dynamic error?

a) By increasing accuracy
b) By increasing precession
c) By reducing sensitivity
d) By reducing time lag

Answer: d
Explanation: Dynamic errorcan be reduced by reducing time lag. Accuracy, precession and sensitivity are static
characteristics. Dynamic errors are caused when the instruments do not respond immediately therefore reducing
time lag will reduce dynamic error.

11. Which among the following is not a dynamic characteristic?

a) Precession
b) Measuring lag
c) Dynamic error
d) Fidelity

Answer: a
Explanation: Precession is not a dynamic characteristic. It comes under static characteristic. Dynamic
characteristics of any sensor or transducer are determined by observing criteria’s that vary rapidly with time.
Precession is the closeness of a single observation among the predefined sets of observations.

12. Which among the following is not a dynamic characteristic?

a) Response speed
b) Accuracy
c) Retardation type measuring lag
d) Time delay lag

Answer: b
Explanation: Accuracy is not a dynamic characteristic. It comes under static characteristic. Static characteristics
are related to steady state response. Accuracy is the observation closest to the true value.

13. Which method can reduce dynamic error?

a) By increasing stability
b) By increasing tolerance
c) By increasing resolution
d) By increasing speed of response

Answer: d
Explanation: Dynamic error can be reduced by increasing speed of response. Stability, tolerance and resolution are
static characteristics. Dynamic errors are caused when the instruments do not respond immediately therefore
increasing speed of response will reduce dynamic error.

14. Which among the following transducer is an example of passive transducer?

a) Photovoltaic cell
b) Thermocouple
c) Piezoelectric transducer
d) Thermistor

Answer: d
Explanation: Thermistor is an example of passive transducer. Passive transducers are those types of transducers
that bring change in passive electrical quantity usually with the help of external power source. Thermistor is a
device that changes its resistance when there is change in temperature.

15. Which among the following transducer is an example of active transducer?

a) LDR (Light dependant sensor)
b) Thermocouple
c) LVDT (linear variable differential transformer)
d) Thermistor

Answer: b
Explanation: Thermocouple is an example of active transducer. Active transducers are those types of transducers
that convert one form of energy to another without any external power source. Thermocouple consists of two rods
made of different metal welded at a junction. When it senses a temperature difference it generates a voltage.

Displacement Sensors

This set of Mechatronics Assessment Questions and Answers focuses on “Displacement Sensors”.
1. An Eddy current type displacement sensor can detect which types of objects?
a) Wooden Objects
b) Metal Objects
c) Plastic Objects
d) Bricks

Answer: b
Explanation: Eddy current type displacement sensor can detect metal objects because it uses high frequency
magnetic field for the detection of objects. When this metallic object come in the range of magnetic field, due to the
electromagnetic induction, eddy current starts to flow through the object in vertical direction which causes a
change in the impedance of the sensor. This change in impedance is used to measure the distance.

2. Which displacement sensor has the slowest response time among Optical type, Eddy current type, Ultrasonic type
and Laser focus type?
a) Optical Type
b) Eddy Current Type
c) Ultrasonic Type
d) Laser Focus Type

Answer: c
Explanation: Ultrasonic type displacement sensor has the slowest response time among all the above mentioned
type sensors. It’s so because it uses ultrasonic sound waves for the measurement while Optical and Laser type
uses light for the measurement which is much faster than the ultrasonic waves. Eddy current type sensors uses
high frequency magnetic field which is also faster than the ultrasonic waves.

3. Which displacement sensor has the lowest accuracy to measure displacement among Optical type, Eddy current
type, Ultrasonic type, Laser focus type?
a) Optical Type
b) Eddy Current Type
c) Ultrasonic Type
d) Laser Focus Type

Answer: c
Explanation: Ultrasonic type displacement sensor has the lowest accuracy to measure displacement among all the
above mentioned type sensors. It’s so because it uses ultrasonic sound waves for the measurement while Optical
and Laser type uses light for the measurement which is much faster than the ultrasonic waves and also has quick
response time. Eddy current type sensors uses high frequency magnetic field which too has a greater response time
compared the ultrasonic type which make it more accurate in measuring distances.

4. What is the International System of length used to measure displacement?

a) Metre
b) Kilo Meter
c) Centimetre
d) Yards

Answer: a
Explanation: The international system of length, also known as the SI unit of length is metres. In MKS system the
standard unit of measuring length is metre, mass in kilogram and time in seconds. This MKS unit is mostly used in
engineering field, but for basic physics field the most common system is the CGS system where the unit of
measurement of length is in centimetres, mass in grams and time in seconds.

5. Displacement sensors can also be used to measure an object’s thickness, height and width.
a) True
b) False

Answer: a
Explanation: In addition to measure the relative displacement of an object, these sensors can also be used to
measure the dimensions of an object. This measurement can be done either by non-contact methods by using light,
sound waves or through making an actual contact with this object.

6. Interferometer can be used for accurate measurement of distance.

a) True
b) False

Answer: a
Explanation: Interferometer can be used for accurate measurement of distance. It can measure small things with
incredibly high accuracy by comparing light or radio beams. It uses the wave pattern interfaces to measure the
distance by comparing reflected or refracted waves coming from objects.
7. ECS in context to displacement measurement stands for ____
a) Electronic Chirp Scaling
b) Extended Chirp Scaling
c) Electronic Chip Scaling
d) Extended Chip Scaling

Answer: b
Explanation: ECS in context to displacement measurement stands for Extended chirp scaling. It’s a commonly used
algorithm used for SAR (Synthetic Aperture Radar) imaging.

8. Bently nevada 3300 xl 5/8mm in an example of which type of sensor?

a) Infrared Sensor
b) Proximitor Sensor
c) Ultrasonic Sensor
d) Temperature Sensor

Answer: b
Explanation: Bently nevada 3300 xl 5/8mm in an example of proximitor sensor. This sensor is mostly used in
industrial sector, it measures the very small movements due to vibrations caused by the big machinaries. It helps
the employee to monitor and control the vibrations in machines.

9. Potentiometer as a displacement sensor works on the principle of ________

a) Mutual Inductance
b) Self Inductance
c) Variable Resistance Transduction
d) Hall Effect

Answer: c
Explanation: Potentiometer as a displacement sensor works on the principle of Variable resistance transduction.
They are linear or rotary potentiometers which converts this rotation in potential difference and this potential
difference is used for calculating the displacement.

10. In capacitive sensors the displacement is measured with respect to change in which internal factor of the
sensor?
a) Capacitance
b) Resistance
c) Inductance
d) Effervescence

Answer: a
Explanation: In capacitive sensors the displacement is measured with respect to change in capacitance of the
sensor. The displacement changes the area of overlap of the charged plates also it moves the dielectric between
the plates which results in change of the dielectric constant and hence both the factors lead in the overall change
of the capacitance.

Position Sensors

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Position Sensors”.
1. Which type of position can be determined by a position sensor?
a) Mechanical position
b) Lateral position
c) Prone position
d) Lithotomy position

Answer: a
Explanation: Position sensors are capable of determining mechanical position of an object with respect to an
arbitrary reference point. In addition, these sensors are also capable of detecting the presence of an object nearby.

2. What is the principle of operation of Potentiometric position sensor?

a) Resistive Effect
b) Hall Effect
c) Mutual Inductance
d) Eddy current effect

Answer: a
Explanation: The Potentiometric position sensor works on the principle of resistive effect. These sensors basically
have a potentiometer built in it whose resistance can be altered using a slider, this resistive track is used as a
sensing element for measuring the distance.

3. How the capacitance in a capacitive position sensor is altered?

a) By changing dielectric constant
b) By changing overlapping area of plates
c) By changing both dielectric constant and overlapping area
d) By adding a resistance in parallel

Answer: c
Explanation: The capacitance in a capacitive position sensor can be changed by altering the dielectric constant as
well as by changing overlapping area of the plates. Dielectric change can be achieved by changing the material
placed between the plates, while the change in overlapping area can be done by fixing a plate and overlapping the
other plate on the body of the first one.

4. Which type of materials can be detected by Eddy current position sensor?

a) Conducting materials
b) Insulating materials
c) Semi-Insulating Materials
d) Amorphous Materials

Answer: a
Explanation: The position of conducting material can be determined by the Eddy current position sensor. Since the
eddy current effect is observed in conducting materials, the sensors working on this principle can detect and
determine the position of the conducting materials only.
5. LIDAR stands for ________
a) Light Detection and Radiation
b) Light Detection and Ranging
c) Lithium Detector and Radiator
d) Lithium Detection and Ranging

Answer: b
Explanation: LIDAR stands for Light Detection and Ranging. It emits optical laser light in pulses and can detect
the X,Y,Z co-ordinates of an object. This technology is widely used in archaeological surveys.

6. LVDT position sensor is a capacitive type of position sensor.

a) True
b) False

Answer: b
Explanation: LVDT is not a capacitive type of position sensor. It’s an inductive type of position sensor. It stands
for Linear Variable Differential Transformer. It works on the same principal as an AC transformer. It is very
accurate in measuring linear movements.

7. Proximity sensor is a ____ type of position sensor.

a) contact
b) non-contact
c) eddy current
d) resistive

Answer: b
Explanation: Proximity sensor is a non-contact type of position sensor. There are several type of proximity sensors
that uses electromagnetic fields, light and sound for detection of the objects and their position.

8. OptoNCDT 1420 in an example of which type of position sensor?

a) Infrared type position sensor
b) Proximity type position sensor
c) Ultrasonic type position sensor
d) Laser triangulation type position sensor

Answer: d
Explanation: OptoNCDT 1420 in an example of Laser triangulation type position sensor. This sensor can detect the
position as well as the distance covered by a particular object. They provide very high accuracy and has set a
milestone in the field of position sensing.
9. Inductive proximity sensor works on the principle of ________
a) Mutual Inductance
b) Faraday’s law of Induction
c) Variable Resistance Transduction
d) Hall Effect

Answer: b
Explanation: Inductive proximity sensor works on the principle of Faraday’s law of Induction. According to this, the
magnitude of the electromotive force induced is directly proportional to the change in the magnetic flux that cuts
through it.

10. Which laser sensor is used for measuring very long distances?
a) OptoNCDT ILR 1030
b) OptoNCDT1420
c) EddyNCDT 3300
d) EddyNCDT 3301

Answer: a
Explanation: OptoNCDT ILR 1030 is laser sensor used for computing distance and objects placed at very high
distances. They are very precise and accurate. The range of these sensors varies from 10m to 3000 metres.

Proximity Sensors

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Proximity Sensors”.
1. Which type of material can be sensed by inductive proximity sensor?
a) Wooden type
b) Metallic type
c) Plastic type
d) Glass type

Answer: b
Explanation: Metallic type of material can be sensed by inductive proximity sensor. Inductive proximity sensor works
on the principle of electromagnetic induction, that is it creates a magnetic field which induces an emf(electromotive
force) which used to determine the presence of objects.

2. Will an infrared proximity sensor detect a black object when it comes in suitable range?
a) Yes, It will detect the object
b) No, It will not detect the object
c) Yes but it will produce random output
d) The sensor will stop working

Answer: b
Explanation: No, It will not detect the object if a black object comes in the range of an infrared proximity sensor.
Since infrared proximity sensors work on reflection of Infrared ray from the objects but when these rays hit a
black object, the ray gets absorbed and does not bounce back. So the sensor is unable to detect the object.

3. Which is the emf(electromotive force) induced in a coil if it has 8 turns and rate of change of flux with respect
to time is 0.5?
a) -10 V
b) -25 V
c) 5.5 V
d) -4 V

Answer: d
Explanation:Given:
Number of turns(N)=8
Change of flux with respect to time(dΦ/dt)=0.5
Emf(electromotive force)(e)=-N*(dΦ/dt)
e=>-8*0.5=-4 V
-4 V is the emf (electromotive force) induced in a coil if it has 8 turns and rate of change of flux with respect to
time is 0.5.

4. Which metal will have a larger range of detection by inductive proximity sensor?
a) Iron
b) Aluminium
c) Copper
d) Lead

Answer: a
Explanation: Iron will have a larger range of detection by inductive proximity sensor. A ferrous metal enables a
longer range of detection where as non-ferrous metals can reduce the sensing range by 60%. Iron is a ferrous
metal whereas all others are non-ferrous which is why iron will have a longer range of detection.

5. A proximity sensor requires physical contact.

a) True
b) False

Answer: b
Explanation: A proximity sensor does not require any physical contact. It can detect objects at distant places
without a touch or contact. It uses electromagnetic waves for the detection. Most of the proximity sensor uses
infrared waves for detection.

6. An inductive proximity sensor cannot detect a metallic object if it is wet or dirty.

a) True
b) False

Answer: b
Explanation: An inductive proximity sensor can detect a metallic object even if it is wet or dirty. Inductive proximity
sensor works on the principle of electromagnetic induction, that is it creates a magnetic field which induces an emf
(electromotive force) which used to determine the presence of objects. The water and dirt does not interfere the
magnetic field so it can detect a metallic object even if it is wet or dirty.

7. Which is has the number of turns in a coil if the emf (electromotive force) induced in it is -2.5V and rate of
change of flux with respect to time is 0.5?
a) -1.5 V
b) -2.5 V
c) 5.5 V
d) -3 V

Answer: b
Explanation:Given:
Emf(electromotive force) induced in it is -2.5V
Change of flux with respect to time(dΦ/dt)=0.5
Emf(electromotive force)(e)=-N*(dΦ/dt)
-2.5=-N*0.5
N=5
Therefore, the coil has total 5 turns.

8. Inductive sensors are also referred as “NMR” coils. What does NMR stand for?
a) Nuclei Magneto resonance
b) Nuclei Magnetic resonator
c) Nuclear Magnetic resonator
d) Nuclear Magnetic resonance

Answer: d
Explanation: NMR stands for Nuclear Magnetic resonance. The “NMR (Nuclear Magnetic resonance)” coils detect
the magnetic component of the EM (Electro-magnetic )field linked with the nuclear spin precession in Nuclear
Magnetic resonance.

9. Which metal will have a larger range of detection by inductive proximity sensor?
a) Zinc
b) Steel
c) Copper
d) Lead

Answer: b
Explanation: Steel will have a larger range of detection by inductive proximity sensor. A ferrous metal enables a
longer range of detection where as non-ferrous metals can reduce the sensing range by 60%. Steel is a ferrous
metal whereas all others are non-ferrous which is why Steel will have a longer range of detection.

10. Which is an example of infrared proximity sensor?

a) GP2Y0A41SK0F
b) CMCP793V-500
c) SLB700A/06VA
d) BMP180

Answer: a
Explanation: GP2Y0A41SK0F is an example of infrared proximity sensor. It is used for detecting object in short
range. BMP180 is an example of pressure sensor. SLB700A/06VA is an example of force sensor. CMCP793V-500 is
a velocity sensor.

11. Which is the emf (electromotive force) induced in a coil if it has 10 turns and rate of change of flux with respect
to time is 1?
a) -10 V
b) -25 V
c) 5.5 V
d) -3 V

Answer: a
Explanation:Given:
Number of turns(N) = 10
Change of flux with respect to time(dΦ/dt)=1
Emf(electromotive force)(e)=-N*(dΦ/dt)
e=>-10*1=-10 V
-10 V is the emf (electromotive force) induced in a coil if it has 10 turns and rate of change of flux with respect to
time is 1.

12. A capacitive proximity sensor can detect only metallic object.

a) True
b) False

Answer: b
Explanation: A capacitive proximity sensor can also detect other object other than just metallic object. It can
detect all objects that have a dielectric constant other than air. These type of sensors are widely used in
appliances such as track-pads or touch-screen sensors.
13. A proximity sensor does not work if the temperature exceeds 100 degree Celsius.
a) True
b) False

Answer: b
Explanation: A proximity sensor can work even if the temperature exceeds 100 degree Celsius. They can work on a
wide temperature range which may extends from -40 degree Celsius to 200 degree Celsius and even more. They
can work accurately at any temperature within this range.

14. Which type of proximity sensor can be used as touch sensor?

a) Inductive proximity sensor
b) Capacitive proximity sensor
c) Ultrasonic proximity sensor
d) Photoelectric proximity sensor

Answer: a
Explanation: Capacitive proximity sensor can be used as touch sensor. Capacitive proximity sensors can detect all
objects that have a dielectric constant other than air. When a human finger comes in contact to the sensor, it
immediately responds to this touch.

15. Which type of proximity sensor can detect a magnetic substance even if a wall of non-ferrous substance is made?
a) Magnetic proximity sensor
b) Capacitive proximity sensor
c) Ultrasonic proximity sensor
d) Photoelectric proximity sensor

Answer: a
Explanation: Magnetic proximity sensor can detect a magnetic substance even if a wall of non-ferrous substance is
made. It can detect the objects beyond the normal limit of inductive proximity sensor. Since magnetic field can
penetrate any wall made of ferrous substance, so they can easily detect a magnetic substance placed beyond the
wall.
Motion Sensors

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Motion Sensors”.
1. Which type of lens is generally used in the PIR sensors?
a) Concave lens
b) Convex lens
c) Bifocal lens
d) Fresnel Lens

Answer: b
Explanation: Fresnel lens is most commonly used lens in the PIR sensors. These Lens help to evenly distribute the
Passive Infrared waves around it which facilitates it to detect motion in 180 degrees in all X,Y and Z axis.

2. The Samuel motion sensor works on which principle?

a) Hall effect
b) Inductive effect
c) Doppler effect
d) Capacitive Effect

Answer: c
Explanation: The Samuel motion sensor works on the principle of “Doppler Effect”. It states that, it is the change
in the frequency of light, sound or any other wave in relation to observer who is in motion with respect to wave
source.

3. Tomographic sensors uses which type of waves for motion detection?

a) Radio waves
b) Ultrasonic waves
c) Infrared waves
d) Microwaves

Answer: a
Explanation: Tomographic sensors uses radio-waves for motion detection. They can sense objects when those radio
waves are disrupted. They are generally very costly and are mostly used in the industrial areas.

4. Combined motion sensors are triggered when all the motion sensors detect a motion.
a) True
b) False

Answer: a
Explanation: The Combined motion sensors are triggered when all the motion sensors detect a motion. If any one of
the sensor detect motion then the alarm is not triggered. This facility eliminates the possibility of fake alarms.

5. Microwave motion sensors has more area coverage than the PIR sensors.
a) True
b) False

Answer: a
Explanation: Microwave motion sensors have larger area of coverage than that of the Passive Infrared sensors as
it uses Microwaves for the detection of the objects. They are usually more expensive than the PIR sensors.
6. What is the frequency range of the ultrasonic sound waves used by the ultrasonic sensors?

a) 20000Hz to 25000Hz
b) 25KHz to 50KHz
c) 25Hz to 55Hz
d) 25Hz to 50Hz

Answer: b
Explanation: The Ultrasonic Sensors produces sound waves of frequency in the range of 25KHz to 50KHz. These
Ultrasonic sounds produced by the sensors transmitter bounce back the in the same path when it encounters an
object in its path. The receiver part receives these waves and calculates the distance and displacement accordingly.

7. PIR stands for ____

a) Passive Infrared
b) Pulsating Infrared
c) Pulsating ratio
d) Pulse is radiation

Answer: b
Explanation: PIR stands for Passive infrared. The PIR sensors are most commonly used motion sensors that are
used for detecting motion by recognizing the heat sensors. They are designed to detect body heat and for motion
recognition.

8. RCWL- 0516 is an example of which type of sensor?

a) Infrared Sensor
b) Microwave Radar Sensor
c) Ultrasonic Sensor
d) Temperature Sensor

Answer: b
Explanation: RCWL- 0516 is an example of Microwave radar sensor. It is used as an alternative to the PIR
sensors. They are cheap and more accurate. Due to the usage of the microwaves, they have a greater range of
detecting objects.

9. The distance range of detection of the PIR sensor is ________

a) 5-10 cm
b) 5-7 m
c) Up to 12 m
d) 5-12 cm

Answer: c
Explanation: The range of detection of the PIR sensor is up to 12 meter. They can accurately detect objects in
motion in this range. These sensors constitute of a pyroelectric sensors that can detect different levels of infrared
radiation.

10. “SAW” in respect to acoustic wave technology stands for ______

a) Sound Acoustic Wave
b) Surface Acoustic Wave
c) Simple Acoustic Wave
d) Surface Acoustic Wave

Answer: b
Explanation: “SAW” in respect to acoustic wave technology stands for Surface Acoustic Wave. This wave is used in
the acoustic sensor for detection of motion. It is named so because acoustic wave has to propagate through a
surface as a medium, any change in the propagation path, changes the velocity and other property of wave which
is used to detect motion in these acoustic sensors.

11. A car moves with a speed of 30 km/hr. What will be the speed of the same car measured by a speed sensor
which is placed in a truck which is moving with a speed of 20 km/hr in the same direction?
a) 30 km/hr
b) 50 km/hr
c) 10 km/hr
d) 0 km/hr

Answer: c
Explanation: Speed of the same car measured by a speed sensor which is placed in a truck will be 10 km/hr. Since
both car and the truck moves in the same direction therefore the relative velocity of the car will be 30–
20=>10km/hr.

12. A moving platform moves with a speed of 100 km/hr. What will be the speed of a boy who is running on it with
a speed of 10 km/hr along the motion of the moving track measured by a speed sensor placed on stationary ground?
a) 150 km/hr
b) 160 km/hr
c) 110 km/hr
d) 140 km/hr

Answer: c
Explanation: Speed of the boy measured by a speed sensor who is running on the moving platform will be 110 km/hr.
Since both move in the same direction then the speed of the boy gets added up with the speed of the moving
platform therefore net speed becomes 100+10=110.

13. A car moves with a speed of 60 km/hr. What will be the speed of the same car measured by a speed sensor
which is placed in a bicycle which is moving with a speed of 12 km/hr in the opposite direction?
a) 60 km/hr
b) 72 km/hr
c) 58 km/hr
d) 48 km/hr

Answer: b
Explanation: Speed of the same car measured by a speed sensor which is placed in a bicycle will be 72 km/hr. Since
both car and the truck moves in the opposite direction therefore the relative velocity of the car with respect to
bicycle will be 60+12=>72km/hr.
14. A moving platform moves with a speed of 80 km/hr. What will be the speed of a boy who is running on it with a
speed of 20 km/hr opposite to the motion of the moving track measured by a speed sensor placed on stationary
ground?
a) 50 km/hr
b) 60 km/hr
c) 100 km/hr
d) 160 km/hr

Answer: b
Explanation: Speed of the boy measured by a speed sensor who is running on the moving platform will be 60 km/hr.
Since the boy and the moving platform moves in opposite direction then the speed of the boy gets subtracted with
the speed of the moving platform therefore net speed becomes 80-20=60.

15. A car moves with a speed of 50 km/hr. What will be the speed of a stationary bicycle parked along the roadside
measured by a speed sensor which is placed in the same car?
a) 50 km/hr
b) 60 km/hr
c) 0 km/hr
d) 40 km/hr

Answer: a
Explanation: speed of a stationary bicycle measured by a speed sensor will be 50 km/hr. Since car is moving with a
speed of 50 km/hr therefore relative speed of the bicycle with respect to car will be 50–0=50 km/hr.

Velocity Sensors
This set of Mechatronics Problems focuses on “Velocity Sensors”.
1. Which type of velocity sensor has a fixed permanent magnet attached to it?
a) Pyroelectric type
b) Piezoelectric type
c) Moving coil type
d) Stationary coil type

Answer: c
Explanation: Moving coil type of velocity sensor has a fixed permanent magnet attached to it. The coil inside it has
a relative motion with respect to the stationary magnet. When the coil is in motion, an electromagnetic force is
induced in the coil due to electromagnetic induction. This electromagnetic force is proportional to the velocity of the
moving object.

2. What is the unit in which tachometers measure velocity?

a) Revolution per minute
b) Meter per second
c) Kilometer per hour
d) Rotation per minute

Answer: a
Explanation: Tachometers measure velocity in Revolution per minute (RPM). They also act as revolution counters,
(i.e) they can also count the number of revolution an object has made in the required interval of time.

3. Which type of tachometer contain primary and secondary stators with fixed windings?
a) AC tachometers
b) DC tachometers
c) Alternating tachometers
d) Brushless tachometers

Answer: a
Explanation: AC tachometers contain primary and secondary stators with fixed windings. It provides fixed output
voltage when the rotor is stationary and varying voltage only when the rotor is moving, this varying voltage is
proportional to the velocity of the revolving object.

4. For what purpose, a “tachometer” is used?

a) It is used for calculating velocity in revolution per minute
b) It is used for calculating the number of revolutions
c) It is used for calculating velocity in revolution per second
d) It is used for calculating the velocity in rpm and number of revolutions

Answer: d
Explanation: Tachometer is used to calculate velocity in revolution per minute. It can also be used as a revolution
counter to calculate the number of revolutions the object has made which we have taken into consideration.
5. The Laser surface velocimeter works on dopplers principle.
a) True
b) False

Answer: a
Explanation: The Laser surface velocimeter(LSV) works on dopplers principle or the dopplers effect. According to
dopplers effect, there is change in the intensity of wave (here light wave) when the source and observer move
towards or away from each other.

6. Accelerometer can be used to measure the tilt.

a) True
b) False

Answer: a
Explanation: In addition of measuring the inertial measurement of velocity and position, accelerometers can be also
used to measure the degree of tilt by considering the acceleration due to gravity as reference. These are generally
used in self balancing robots.

7. What does RPM stand for?

a) Rotation per minute
b) Revolution per minute
c) Rounds per minute
d) Rotation per millisecond

Answer: b
Explanation: RPM stands for revolution per minute. It is the most commonly used unit in motor appliances and
motor vehicles for denoting the speed of the crank shaft in the engine.

8. _______ velocity sensor is a type of velocity sensor

a) Infrared
b) Proximitor
c) Piezoelectric
d) Ultrasonic

Answer: c
Explanation: Piezoelectric velocity sensor is a type of velocity sensor. The output of the velocity sensor is
proportional to the velocity of the object. Since the output of the sensor is very small so it mostly needs an
amplifier for using it for any application.

9. LSV in terms of velocity measurement stands for ________

a) Laser Surface Velocimeter
b) Laser Surface Velocity meter
c) Linear Surface Velocimeter
d) Linear Surface Velocity meter

Answer: a
Explanation: LSV in terms of velocity measurement stands for Laser surface velocimeter. It is a non-contact type
velocity measuring tool which uses the laser doppler effect for evaluating the light scattered from the moving
object.

10. Which is a type of velocity sensor?

a) MSP430G2ET
b) CMCP793V-500
c) MPU 6050
d) L298N

Answer: b
Explanation: CMCP793V-500 is a type of velocity sensor. It is used to examine very small vibrations in terms of
velocity. Since these received signals are of very low frequency, they need an amplifier to amplify the received signal
and convert them in terms of velocity.

Force Sensors

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Force Sensors”.
1. Which is the most common load cell used in the force sensors?
a) Hydraulic load cells
b) Strain-Gauge based load cells
c) Pneumatic load cells
d) Capacitive load cells

Answer: b
Explanation: Strain-Gauge based load cells are the most common load cell used in the force sensors. It is a
transducer that is used for sensing the force, it converts the applied force into electrical signals which is used for
sensing the amount of load that is applied.

2. What is the standard capacity of tension load cells to measure load?

a) 25,000 to 100,000 lbs
b) 25,00 to 10,000 lbs
c) 25,000 to 100,000 Kg
d) 25,00 to 10,000 Kg

Answer: a
Explanation: The standard capacity of tension cells to measure load ranges from 25,000 to 100,000 lbs. Tension
cells calculate the applied force based upon the tension applied on beams or cables. Though this range can be
exceeded in the custom ones.

3. Which force sensor is not a strain gauge type force sensor?

a) Load pins
b) Shear beams
c) Tension links
d) ALC annular load cell

Answer: d
Explanation: ALC annular load cell sensor is not a strain gauge type force sensor. It is a capacitive load cell or a
capacitive based load sensor. Other all the remaining are stress gauge type force sensors which are used to
measure tension or sheer forces.

4. Which transducer does not require any external power supply for working?
a) Strain gauge transducer
b) Piezoelectric Crystals
c) Hydraulic transducer
d) Pneumatic transducer

Answer: b
Explanation: Piezoelectric Crystals does not require any external power supply for working. They generate a voltage
when an external force is applied on it which is directly proportional to the external applied force. These sensors
need special indicators for measuring that voltage change.

5. RFI (Radio frequency interference), moisture and temperature cannot interfere with the signals sent by the
load cells.
a) True
b) False

Answer: b
Explanation: RFI (Radio frequency interference), moisture and temperature can interfere with the signals sent by
the load cells. RFI acts as electrical noise to the force transducer’s signal. Moisture can wick itself the cables and
can create a difference in capacitance between the signal lines. Temperature affects the resistance of the cables
and thus can create an interference in the original signal.

6. Higher capacitive load cells can ensure Wind loading and shock loading.
a) True
b) False

Answer: a
Explanation: Higher capacitive load cells can ensure Wind loading and shock loading. Wind and shock waves can affect
the actual measurement of weight or force calculated. Using higher capacitive load cells will eliminate the very
small changes caused by these external factors and only give the correct ones in the output.

7. RFI is electrical noise to load cells. What does RFI stand for?
a) Radio Frequency Interface
b) Radio Frequency Interference
c) Relay Frequency Interference
d) Relay Frequency Interface
Answer: b
Explanation: RFI stand for Radio Frequency Interference. Radio frequency interference is also called as
Electromagnetic interference (EMI). It is electrical noise to the load cell signal sent from the sensor.

8. What causes the problem of 60-hertz hum?

a) In-appropriate voltage supply
b) Absence of digital to analog converter
c) In-appropriate current supply
d) Absence of analog to digital converter

Answer: d
Explanation: Absence of analog to digital converter can causes the problem of 60-hertz hum. The controllers is
advised to have a digital to analog converter which can be synchronised with the 60 Hz frequency signals in the
power supply lines.

9. What is the phenomenon (principle) on which magnetoelastic force sensors work?

a) Villari effect
b) Hall effect
c) Lenz law
d) Mutual Induction

Answer: a
Explanation: Magnetoelastic force sensors work on “Villari effect” also known as the magnetoelastic effect. It was
named after an Italian physicist who discovered it. This effect states that when a ferromagnetic material is
subjected to stress then there is change in the magnetic flux. This effect is known as the “Villari effect”.

10. Which is an example of force sensor?

a) MSP430G2ET
b) CMCP793V-500
c) SLB700A/06VA
d) L298N

Answer: c
Explanation: SLB700A/06VA is an example of force sensor. It is a strain transducer that converts the strain to
electrical signals. MSP430G2ET is a development board manufactured by the “TEXAS INSTRUMENTS”,
CMCP793V-500 is a velocity sensor and L298N is a motor driver.

11. What is the value of force measured by a force sensor lying on a plane ground if a block of mass 3 kg is kept on
it and a normal upward tensile force of 5 Newton is applied on the block? (Take acceleration due to
gravity=10m/s2)
a) 15 Newton
b) 25 Newton
c) 30 Newton
d) 24 Newton

Answer: b
Explanation: Given:
Mass of block=3kg
Normal upward force=5Newton
Net force due to block=Force due to mass of block-Normal upward force
Force due to mass of block=mass*acceleration (here acceleration due to gravity)
Force due to mass of block=3*10=>30N
Net force due to block=30N-5N=>25N

12. What is the value of force measured by a force sensor lying on a plane ground if a block of mass 2 kg is kept on
it and a normal upward tensile force of 4 Newton is applied on the block? (Take acceleration due to
gravity=10m/s2)
a) 15 Newton
b) 20 Newton
c) 16 Newton
d) 24 Newton

Answer: c
Explanation: Given:
Mass of block=2kg
Normal upward force=4 Newton
Net force due to block=Force due to mass of block-Normal upward force
Force due to mass of block=mass*acceleration (here acceleration due to gravity)
Force due to mass of block=2*10=>20N
Net force due to block=20N-4N=>16N

13. What is the value of force, measured by a force sensor placed on the wall; if a rigid block of mass 3kg is
smashed against the wall with an acceleration of 5m/s 2? (Take acceleration due to gravity=10m/s 2)
a) 15 Newton
b) 20 Newton
c) 16 Newton
d) 0 Newton

Answer: a
Explanation: Given:
Mass of block = 3 kg
Acceleration of block=5m/s2
Force experienced by sensor=mass*acceleration
Force experienced by sensor=3*5=>15 N

14. What should be the acceleration of a rigid body of mass 5kg; if a force sensor measures a normal collision impact
force of 15N? (Ignore acceleration due to gravity)
a) 5 m/s2
b) 13 m/s2
c) 6 m/s2
d) 3 m/s2

Answer: d
Explanation: Given:
Mass of block=5 kg
Force measured by the force sensor=15N
Force experienced by sensor=mass of body*acceleration of body
Acceleration of body=Force experienced by sensor/mass
Acceleration of body=15N/5kg=>3m/s 2

Acceleration Sensors

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Acceleration Sensors”.
1. What will be the value measured by an accelerometer in free fall?
a) Zero
b) Infinite
c) Error
d) 9.81

Answer: a
Explanation: In a free fall the accelerometer will measure value=0. In a stationary state the accelerometer will
measure the acceleration due to gravity as 9.81 m/s 2 but in a free fall the acceleration of the falling accelerometer
is also 9.81 m/s2 in the same direction, therefore the relative acceleration of the accelerometer becomes zero.

2. Which is the name of the accelerometer that is used to measure the gravity of the earth?
a) MPU6050
b) Gravitymeter
c) Gravitometer
d) Gravimeter

Answer: d
Explanation: Gravimeter are the accelerometer that is used to measure the gravity of the earth. The gravity of
the earth varies from place to place depending upon the type of plain, plateau etc. This determination of
acceleration due to gravity is called gravimetry.

3. What is the exact value of acceleration due to gravity taken in consideration?

a) 10 m/s2
b) 9.80665 m/s2
c) 9 m/s2
d) 0 m/s2

Answer: b
Explanation: The exact standard acceleration due to gravity is taken as 9.80665 m/s 2. For general calculations it is
assumed to be 10 m/s2. It the acceleration in which the earth pulls all the object present on the surface of earth.
This acceleration varies at the poles of the earth.
4. Which element is mostly used in the capacitive accelerometers for sensing?
a) Germanium
b) Silicon
c) Lead
d) Carbon

Answer: b
Explanation: Silicon is mostly used in the capacitive accelerometers for sensing. It is relatively cheap and exhibits
far better performance in the low frequency range. They can provide a higher stability and linearity when operated
in servo mode.

5. MEMS stands for ________

a) Micro electric mechanical system
b) Micro electro mechanical system
c) Mini electro mechanical system
d) Mini electronic mechanical system

Answer: b
Explanation: MEMS stands for Micro electro mechanical system. Accelerometers, Gyroscopes and pressure sensors
are MEMS sensors. It is a technology using which most of the accelerometers and other sensors are designed.

6. Accelerometers can be used for sensing mechanical vibrations.

a) True
b) False

Answer: a
Explanation: Accelerometers can be used for sensing mechanical vibrations. They can detect even very precise
vibrations in the machine. Since the vibration is in single plane a two axis accelerometer is best suited for the
measurement.

7. Acceleration is a ______ quantity.

a) scalar
b) vector
c) tensor
d) resistive

Answer: b
Explanation: Acceleration is a vector quantity. It is a vector quantity because it depends on both, magnitude of
acceleration as well as the direction of acceleration. Had it been only dependent on magnitude, it would be a scalar
quantity but it is not so.

8. MPU6050 in an example of which type of sensor?

a) Acceleration sensor
b) Proximity Sensor
c) Ultrasonic sensor
d) Laser sensor

Answer: a
Explanation: MPU6050 is an example of Acceleration sensor. It consists both 3 axis accelerometer and 3 axis
gyroscope, which is capable of measuring very precise movements and accelerations.

9. Piezoelectric accelerometers converts ________ energy to ______energy.

a) mechanical, sound
b) mechanical, electrical
c) sound, electrical
d) sound, electrical

Answer: b
Explanation: Piezoelectric accelerometers converts mechanical energy to electrical energy. The word piezoelectric is
derived from a Greek word “piezein” which means to press or squeeze. When any mechanical variable such as force
or shock is applied on the input, then it produces subsequent electrical signals which is used to measure its
magnitude.

10. Which is an example of accelerometer?

a) OptoNCDT ILR 1030
b) OptoNCDT 1420
c) ADXl 335
d) EddyNCDT 3301

Answer: c
Explanation: ADXl 335 is an example of accelerometer. OptoNCDTILR 1030 and OptoNCDT 1420 are laser sensor
used for computing distance and objects placed at very high distances. EddyNCDT 3301 is a Eddy currents sensor.

11. A free falling heavy object will have more acceleration than a free falling light object if released from a same
height. (Ignore air resistance)
a) True
b) False

Answer: b
Explanation: A free falling heavy object will not have more acceleration than a free falling light object if released
from a same height. Both the object will experience same acceleration due to gravity, which is why a free falling
light object and heavy object will reach the ground at the same time if released from a same height.

12. Who invented the first accelerometer?

a) Grueblerowen
b) Joseph Henry
c) George Atwood
d) Walther Bothe

Answer: c
Explanation: George Atwood invented the first accelerometer. The first accelerometer was invented in the year
1783 and was originally named as Atwood machine. This machine was used to calculate linear accelerations.

13. What was the original name of first accelerometer?

a) Eskimometer
b) Atwood machine
c) Asimo machine
d) Pepper

Answer: b
Explanation: The original name of first accelerometer was Atwood machine. It was named after its inventor
George Atwood. He was an English physicist who invented the first accelerometer in the year 1783.

14. AC (Alternating Current) response accelerometer cannot measure constant or static acceleration.
a) True
b) False

Answer: a
Explanation: AC (Alternating Current) response accelerometer cannot measure constant or static acceleration such
as acceleration due to gravity. They are designed to determine dynamic accelerations and events which changes
regularly.

15. DC (Direct Current) response accelerometer cannot measure dynamic acceleration.

a) True
b) False

Answer: b
Explanation: DC (Direct Current) response accelerometer can measure dynamic acceleration as well as static
acceleration such as acceleration due to gravity. However, AC (Alternating Current) response accelerometer cannot
measure constant or static acceleration. They are designed to determine dynamic accelerations and events which
changes regularly.

Torque Sensors

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Torque Sensors”.
1. Which is the formula for measurement of torque, provided “r” is the position vector and “f” is the force vector?
a) f*r*sinθ
b) f*r*cosθ
c) f*r*tanθ
d) f*r*secθ

Answer: a
Explanation: The formula for measurement of torque, provided “r” is the position vector and “f” is the force vector
is f*r*sinθ. Torque is the cross product of the force vector and position vector (i.e) t(torque)=f x r, which ultimately
gives f*r*sinθ.
2. What is the unit in which torque is measured?
a) Newton meter
b) Meter per second
c) Kilometer per hour
d) Rotation per minute

Answer: a
Explanation: The SI unit of torque is Newton-meter (Nm). Torque is defined as force multiplied by the position
vector and Sine of the angle between the force vector and position vector. The corresponding SI unit of
measurement is Newton and meter. So the SI unit is newton meter.

3. Which sensor is a type of inline torque sensor?

a) M425
b) FF425
c) RS425
d) ADXL345

Answer: a
Explanation: M425 sensor is a type of inline torque sensor. FF425 is a dual flange torque sensor. RS425 is
completely contactless type torque sensor. ADXL345 is a 3 axis accelerometer.

4. What type of torque is associated with braking system of a vehicle, when brakes are applied?
a) Stationary torque
b) Dynamic torque
c) Static torque
d) Distinctive torque

Answer: c
Explanation: When brakes are applied in a moving vehicle, static torque is generated. It is because the force applied
by the brakes is static as there is no acceleration involved, so the corresponding torque generated is called static
torque.

5. Inline torque measurement is more accurate than reaction torque measurement.

a) True
b) False

Answer: a
Explanation: Inline torque measurement is more accurate than reaction torque measurement. It is so because inline
torque sensors are placed beside the torque carrying components, this eliminates the possibility of any other
external parasitic torques to interfere.

6. Reaction torque measurement is done when acceleration is required.

a) True
b) False

Answer: b
Explanation: Reaction torque measurement is done when acceleration is not required. It is also called as static
torque measurement. The word “static” itself denotes that the item on which the torque is measured should not
be in motion.

7. What varies in a strain gauge torque sensor when force is applied?

a) Resistance
b) Inductance
c) Capacitance
d) Velocity

Answer: a
Explanation: Resistance varies in a strain gauge torque sensor when force is applied. A strain gauge has some
electrical conductive material printed on an insulated substrate, when force is applied over it the material
experiences a strain and the resistance of the material changes.

8. The two types of torque are: ______ torque and ________ torque.
a) Static torque, dynamic torque
b) Static torque, distinctive torque
c) Stationary torque, non-stationary torque
d) Dynamic, non-dynamic
Answer: a
Explanation: The two types of torque are: Static torque and dynamic torque. The torque generated when there is
no relative acceleration is called static torque. Whereas the torque generated due to dynamic acceleration or
deacceleration is called dynamic torque.

9. SAW torque sensors are a wireless torque sensor. SAW stands for ________
a) Sound Acoustic Wave
b) Surface Acoustic Wave
c) Simple Acoustic Wave
d) Surface Acoustic Wave

Answer: b
Explanation: “SAW” stands for Surface Acoustic Wave. This wave is used in the acoustic sensor for detection of
motion. It is named so because acoustic wave has to propagate through a surface as a medium, any change in the
propagation path, changes the velocity and other property of wave which is used to detect motion in these
acoustic torque sensors.

10. Which is a type of torque sensor?

a) CMCP793V-500
b) FF425
c) MPU 6050
d) L298N

Answer: b
Explanation: FF425 is a type of torque sensor. CMCP793V-500 is a type of velocity sensor. MPU 6050 is a 6 axis
gyroscope and accelerometer. L298N is a motor driver with dual-H bridge.

11. What is the torque provided by a flywheel which is being rotated with a force of 2N and radial distance of point
of application of the force from the centre is 1m? (Consider the radial distance vector and force vector are
perpendicular to each other)
a) 2 Nm
b) 3 Nm
c) 4 Nm
d) 5 Nm

Answer: a
Explanation: Given:
Force (f) = 2N
Radial distance(r)=1m
Angle between radial distance vector and force vector(θ)=90°
We know; Torque (t)=f*r*sinθ
Torque (t)=2*1*sin (90°) [since sin (90°)=1]
Torque (t)=2 Nm

12. What is the torque provided by a flywheel which is being rotated with a force of 3N and radial distance of
point of application of the force from the centre is 0.5m? (Consider the radial distance vector and force vector are
perpendicular to each other)
a) 2 Nm
b) 3 Nm
c) 1.5 Nm
d) 5 Nm

Answer: c
Explanation: Given:
Force (f) = 3N
Radial distance(r)=0.5m
Angle between radial distance vector and force vector (θ)=90°
We know; Torque (t)=f*r*sinθ
Torque (t)=3*0.5*sin (90°) [since sin (90° )=1]
Torque (t)=1.5 Nm

13. What is the torque provided by a rotating object which is being rotated with a force of 6N and radial distance
of point of application of the force from the centre is 2m? (Consider the radial distance vector and force vector are
at 30° to each other)
a) 3 Nm
b) 6 Nm
c) 1 Nm
d) 5 Nm

Answer: b
Explanation: Given:
Force(f)=6N
Radial distance(r)=2m
Angle between radial distance vector and force vector (θ)=30°
We know; Torque (t)=f*r*sinθ
Torque (t)=6*2*sin(30°) [since sin(30°)=1/2]
Torque (t)=6Nm

14. What is the force provided for rotating object which is being rotated with a torque of 10 Nm and radial
distance of point of application of the force from the centre is 4m? (Consider the radial distance vector and force
vector are at 30° to each other)
a) 13 N
b) 16 N
c) 10 N
d) 5 N

Answer: d
Explanation: Given:
Torque (t)=10Nm
Radial distance(r)=4m
Angle between radial distance vector and force vector (θ)=30°
We know; Torque (t)=f(force)*r(radial distance)*sinθ
10 = f*4*sin (30°) [since sin (30°)=1/2]
F (force)=5N

15. If the radial distance vector and force vector are in the same line then the torque will be 0.
a) True
b) False

Answer: a
Explanation: If the radial distance vector and force vector are in the same line then the torque will be 0. Torque is
the cross product of the force vector and position vector (i.e) t(torque)=f x r, which ultimately gives f*r*sinθ. If
radial distance vector and force vector are in the same line then θ=0 and sin0°=0. Therefore Torque=0.

Fluid Pressure Sensors

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Fluid Pressure Sensors”.
1. How is pressure (p) defined in terms of force(F) and area(A)?
a) p = F*A
b) p = F+A
c) p = F/A
d) p = F-A

Answer: c
Explanation: Pressure is defined as force per unit area (i.e) pressure (p) = force (F)/Area of cross-section (A). The
standard unit of force and area taken is Newton and (meter)2respectively.

2. What is the SI unit of pressure?

a) Pascal
b) Barye
c) Atm
d) Newton

Answer: a
Explanation: Pascal is the SI unit of pressure. 1 pascal = 1 Newton of force applied on 1 square meter of area.
Barye is the CGS unit of pressure. Atm is used to measure atmospheric pressure, whereas Newton is unit of force.

3. 1 atm = ____ pascal or ______bar.

a) 101325, 101.325
b) 101325, 9.81
c) 1.01325, 101325
d) 101325, 1.01325

Answer: d
Explanation: 1 atm = 101325 Pascal or 1.01325 bar. 1 atm is the atmospheric pressure above the sea level (i.e)
pressure exerted by the atmosphere above the sea level. Pascal is the SI unit of pressure and 1 atmospheric
pressure is equal to 101325 Pascal.

4. Whose pressure can be determined by the bourdon tube pressure gauge?

a) Solids
b) Fluids
c) Only Gas
d) Only liquids

Answer: b
Explanation: Bourdon tube can determine the pressure of the fluids. Fluids include all the materials that can flow,
be it gas or liquid. Bourdon tube is curved, hollow tube. When the pressure in the tube increases, it causes a
deformation in the shape of the tube. This deformation is used to determine the amount of pressure exerted by
the fluid in the tube.

5. Absolute pressure is the sum of over pressure and atmospheric pressure.

a) True
b) False

Answer: a
Explanation: Absolute pressure is the sum of over pressure and atmospheric pressure. Over pressure is commonly
known as gauge pressure, therefore P(abs)={P(over) or P(gauge)}+P(atm).

6. Gauge pressure is the summation of absolute pressure and atmospheric pressure.

a) True
b) False

Answer: b
Explanation: Gauge pressure is the not summation of absolute pressure and atmospheric pressure. It the
difference between the absolute pressure and atmospheric pressure (i.e)P(gauge)=P(abs)-P(atm).

7. Which is not equal to 1 atmospheric pressure?

a) 101325 Pascal
b) 1.01325 Bar
c) 101.325 torr
d) 760 torr

Answer: c
Explanation: 101.325 torr is not equal to 1 atmospheric pressure. 1 atmospheric pressure is equal to 101325 pascal
or 1.01325 bar or 760 torr. Pascal is the SI unit of pressure.

8. Which fluid is commonly used in U-tube manometers as a reference, in determining the pressure of the liquid?
a) Sodium
b) Argon
c) Water
d) Mercury

Answer: d
Explanation: Mercury is commonly used fluid in U-tube manometers as a reference, in determining the pressure of
the liquid. The specific gravity of mercury is 13.6 which mean that it is 13.6 times heavier than water.

9. What is the pressure experienced by a wall, if a brick is thrown with a force 10 Newton and cross-section area of
contact is 2 square metres?
a) 5 Pascal
b) 5 Atm
c) 5 barye
d) 1 Atm

Answer: a
Explanation: Given:
Force of brick thrown=10 Newton
Cross-section area=2m2
Since pressure (p)=Force of brick thrown (F)/Area of cross-section (A),
P=10N/2m2=5 pascal.

10. Which is an example of pressure sensor?

a) MSP430G2ET
b) CMCP793V-500
c) SLB700A/06VA
d) BMP180

Answer: d
Explanation: BMP180 is an example of pressure sensor. SLB700A/06VA is an example of force sensor.
MSP430G2ET is a development board manufactured by the “TEXAS INSTRUMENTS” and CMCP793V-500 is a
velocity sensor.

11. What is the pressure experienced by a pressure sensor, if a rigid body is thrown normally with a force 5 Newton
and cross-section area of contact is 1 square metre?
a) 5 Pascal
b) 5 Atm
c) 5 Barye
d) 1 Atm

Answer: a
Explanation: Given;
Force of brick thrown=5 Newton
Cross-section area=1 m2
Since pressure (p) = Force of brick thrown (F)/Area of cross-section (A),
P=5N/1m2=5 Pascal.

12. What is the absolute pressure experienced by a pressure sensor, if the atmospheric pressure of a fluid is 2
atm, gauge pressure is 5 atm and differential pressure is 3 atm?
a) 5 pascal
b) 5 Atm
c) 7 barye
d) 7 Atm

Answer: d
Explanation: Given;
Atmospheric pressure=2 atm
Gauge pressure=5atm
Differential pressure=3 atm
Absolute pressure=Gauge pressure+Atmospheric pressure
Absolute pressure=5atm+2atm => 7atm

13. What is the gauge pressure experienced by a pressure sensor, if the atmospheric pressure of a fluid is 1 atm,
absolute pressure is 6 atm and differential pressure is 2 atm?
a) 5 pascal
b) 5 Atm
c) 5 barye
d) 1 Atm

Answer: b
Explanation: Given;
Atmospheric pressure = 1 atm
Absolute pressure = 6 atm
Differential pressure = 3 atm
Gauge pressure = Absolute pressure-Atmospheric pressure
Gauge pressure = 6 atm-1atm => 5atm

14. What is the cross-section area of contact, if a brick is thrown with a force 10 Newton and the pressure
experienced by a wall is 5 Pascal?
a) 2m2
b) 5m2
c) 4m2
d) 3m2

Answer: a
Explanation: Given:
Force of brick thrown=10 Newton
Pressure experienced by a wall=5 Pascal
Since pressure (p)=Force of brick thrown (F)/Area of cross-section (A),
5 Pascal=10/A
Area of cross-section (A)=2m2
15. What is the pressure experienced by a pressure sensor, if a rigid body is thrown normally with a force 6 Newton
and cross-section area of contact is 2 square metres?
a) 3 Pascal
b) 3 Atm
c) 3 Barye
d) 12 Atm

Answer: a
Explanation: Given:
Force of brick thrown=6 Newton
Cross-section area=2m2
Since pressure (p)=Force of brick thrown (F)/Area of cross-section (A),
P=6N/2m2=3 Pascal.

Liquid Flow Sensors

This set of Mechatronics Multiple Choice Questions & Answers (MCQs) focuses on “Liquid Flow Sensors”.
1. What is the flow rate of a liquid flowing through a cylindrical pipe of cross section area 0.5m 2 and velocity of the
liquid is 0.5m/s?
a) 0.5
b) 0.75
c) 0.25
d) 1

Answer: c
Explanation: Given:
Cross section area=0.5 m2
Velocity of the liquid=0.5 m/s
Flow rate=Cross section area*Velocity of the liquid
Flow rate=0.5*0.5=0.25m3/s

2. What is the flow rate of a liquid flowing through a cylindrical pipe of radius 0.2 m and velocity of the liquid is
0.6m/s?
a) 0.5
b) 0.07536
c) 0.0157
d) 0.0628

Answer: b
Explanation: Given:
Radius(r)=0.1m
Cross section area=pi*r2
Cross section area=3.14*(0.2)2 => 0.1256
Velocity of the liquid=0.6m/s
Flow rate=Cross section area*Velocity of the liquid
Flow rate=0.1256*0.6 => 0.07536m3/s

3. What is the flow rate of a liquid flowing through a cylindrical pipe of radius 0.1 m and velocity of the liquid is
0.5m/s?
a) 0.5
b) 0.75
c) 0.0157m3/s
d) 1

Answer: c
Explanation: Given:
Radius(r)=0.1m
Cross section area=pi*r2
Cross section area=3.14*(0.1)2=>0.0314
Velocity of the liquid=0.5 m/s
Flow rate= Cross section area*Velocity of the liquid
Flow rate=0.0314*0.5 => 0.0157m3/s

4. What is the SI unit of volumetric flow rate?

a) m2/s
b) m3/s
c) m/s
d) m3/s2

Answer: b
Explanation: m3/s is the SI unit of volumetric flow rate, where “m” and “s” denotes meter and seconds respectively.
Volumetric flow rate represents the rate at which a particular volume of fluid flows through a cross section area
in 1 second.

5. High turbidity is bad for aquatic life.

a) True
b) False

Answer: a
Explanation: High turbidity is bad for aquatic life. Turbidity refers to the amount of sediments present in the
water. High turbidity can block the sunlight which is essential for the aquatic plants to live. The turbidity contains
several pathogens which may be harmful for the aquatic life.

6. Ultrasonic flow meter works on Doppler Effect.

a) True
b) False

Answer: a
Explanation: Ultrasonic flow meter works on Doppler Effect. Ultrasonic flow meters are generally used for
monitoring dirty water such as sewage waste water. It can detect large suspended particles and bubbles flowing
through the channel.

7. Which is a gas flow meter?

a) MSP430G2ET
b) CMCP793V-500
c) FLUXUS G601
d) FMA-PC16

Answer: c
Explanation: FLUXUS G601 is a gas flow meter. FMA-PC16 is a mass flow meter. MSP430G2ET is a development
board manufactured by the “TEXAS INSTRUMENTS” and CMCP793V-500 is a velocity sensor.

8. What is the flow rate of a liquid flowing through a cylindrical pipe of radius 0.2 m and velocity of the liquid is 0.5
m/s?
a) 0.5
b) 0.75
c) 0.0157
d) 0.0628

Answer: d
Explanation: Given:
Radius(r)=0.1m
Cross section area=pi*r2
Cross section area=3.14*(0.2)2=>0.1256
Velocity of the liquid=0.5 m/s
Flow rate= Cross section area*Velocity of the liquid
Flow rate=0.1256*0.5=>0.0628m3/s

9. What is the flow rate of a liquid flowing through a cylindrical pipe of cross section area 0.2m 2 and velocity of the
liquid is 0.5 m/s?
a) 0.5
b) 0.75
c) 0.25
d) 0.1

Answer: d
Explanation: Given:
Cross section area=0.2m2
Velocity of the liquid=0.5m/s
Flow rate=Cross section area*Velocity of the liquid
Flow rate=0.2*0.5=0.1m3/s

10. Which is a mass flow meter?

a) MSP430G2ET
b) CMCP793V-500
c) SLB700A/06VA
d) FMA-PC16

Answer: d
Explanation: FMA-PC16 is a mass flow meter. SLB700A/06VA is an example of force sensor. MSP430G2ET is a
development board manufactured by the “TEXAS INSTRUMENTS” and CMCP793V-500 is a velocity sensor.

11. Which liquid has lowest density?

a) Acetic acid
b) Pure water
c) Olive oil
d) Sea Water

Answer: c
Explanation: Olive oil has lowest density. Its density is 911kg/m 3. Pure water has a density of 1000 kg/m3 and Sea
Water has a density of 1022 kg/m3. Acetic acid has the highest density among the four, with a density of 1049
kg/m3.

12. Which liquid will have more mass for same amount of volume?
a) Brine
b) Chloroform
c) Olive oil
d) Sea Water

Answer: b
Explanation: We know density=mass/volume
Since volume is constant so, mass is directly proportional to liquid. Therefore the liquid with highest density has the
highest mass.
Olive oil has density is 911 kg/m3. Sea Water has a density of 1022kg/m3. Brine has a density of 1230kg/m3.
Chloroform has the highest density among the four, with a density of 1489 kg/m 3.
Therefore chloroform will have the highest mass.

13. Which liquid will have more mass for same amount of volume?
a) Coconut oil
b) Phosgene
c) Castor oil
d) Sea Water

Answer: b
Explanation: We know density=mass/volume
Since volume is constant so, mass is directly proportional to liquid. Therefore the liquid with highest density has the
highest mass.
Castor oil has density is 952 kg/m3. Sea Water has a density of 1022kg/m3. Coconut oil has a density of
930kg/m3. Phosgene has the highest density among the four, with a density of 1378kg/m 3.
Therefore Phosgene will have the highest mass.

14. Which is a Liquid flow sensor?

a) SLF3X
b) CMCP793V-500
c) SLB700A/06VA
d) FMA-PC16

Answer: a
Explanation: SLF3X is a Liquid flow sensor. It is durable, stable and provides long time durability for various
applications. FMA-PC16 is a mass flow meter. SLB700A/06VA is an example of force sensor. CMCP793V-500 is a
velocity sensor.

15. What is the SI unit of flow rate of a Liquid or fluid?

a) m3/s
b) m2/s
c) m/s
d) m3/s2

Answer: a
Explanation: m3/s is the SI unit of flow rate of a Liquid. Flow rate is calculated by considering unit of volume
flowing in one second. SI unit of volume is m3 and time is seconds, which gives the SI unit of flow as m3/s.

Selection of Sensors
This set of Mechatronics Question Paper focuses on “Selection of Sensors”.
1. Which factor affects the least while selection of sensor?
a) Size
b) Accuracy
c) Colour
d) Durability

Answer: c
Explanation: Colour of a sensor affects the least while selection of sensor. Accuracy of the sensor is needed in order
to achieve precise results. Size of the sensor depends on the area of application. And for the sensor to last long and
give the same results, it must be durable enough.

2. Which sensor should one prefer for accurate measurement of distance upto 1 meter?
a) Ultrasonic sensor
b) Infrared sensor
c) PIR sensor
d) Photoresistor sensor

Answer: a
Explanation: Ultrasonic sensor should one prefer for accurate measurement of distance upto 1 meter. Infrared
sensor can also be used for measuring distance but its range is less than a meter. PIR sensor and Photoresistor
sensor cannot be used for measuring distance.

3. Which sensor one should prefer for detecting black objects?

a) Ultrasonic sensor
b) Infrared sensor
c) PIR sensor
d) Photoresistor sensor

Answer: a
Explanation: Ultrasonic sensor one should prefer for detecting black objects. Infrared sensor and PIR sensor cannot
detect black objects, because they work on reflection of Infrared ray from the objects and black objects does not
reflect infrared rays.
4. IR sensors can’t work in dark environment.
a) True
b) False

Answer: b
Explanation: IR sensors can work in dark environment. It does not require an external light source. They only need
an Infrared emitter or any source of infrared and these sources are present on the sensor itself. So it can work in
dark.

5. Arduino UNO is a microcontroller board based on ESP8266 IC.

a) True
b) False

Answer: b
Explanation: Arduino UNO is not based on ESP8266 IC. It is a microcontroller board based on Atmega328P. It is
a general purpose development board which contains 6 analog pins and 14 digital pins out of which 6 pins can be
used as PWM (pulse width modulation) outputs.

6. Which IC (integrated circuit) is present on NodeMCU?

a) ESP8266
b) Atmega326
c) Atmega328P
d) ESPN8266

Answer: a
Explanation: ESP8266IC (integrated circuit) is present on NodeMCU. It is a wifi enabled chip. It is developed by
Espress if Systems. It is a low cost Wifi chip with TCP/IP protocol. Atmega328P is present on the Arduino UNO
development board.

7. Which colour does not reflect infrared rays?

a) White
b) Black
c) Red
d) Green

Answer: b
Explanation: Black colour does not reflect infrared rays. All other colour reflects infrared rays. This is the reason
why infrared sensors or any other infrared based sensor is unable to detect black coloured objects.

8. HC-SR04 is an example of which type of sensor?

a) Infrared Sensor
b) Microwave Radar Sensor
c) Ultrasonic Sensor
d) Temperature Sensor

Answer: c
Explanation: HC-SR04 is an example of Ultrasonic Sensor. It is one of the most widely used ultrasonic sensor for
robotic or arduino projects. It is cheap and gives accurate measurement of distance upto few metres.

9. What is the maximum distance range of detection of the HC-SR04?

a) 10 cm
b) 10 m
c) 5 feet
d) 13 feet

Answer: d
Explanation: 13 feet is the maximum distance range of detection of the HC-SR04. HC-SR04 is a Ultrasonic Sensor.
It is cheap and one of the most widely used ultrasonic sensor for robotic or arduino projects.

10. What is the maximum range of HC-05?

a) 5 metre
b) 10 meter
c) 20 meter
d) 50 meter

Answer: b
Explanation: 10 meter is the maximum range of HC-05. HC-05 is a Bluetooth sensor which uses 2.45 gigaHertz
frequency band for transmission. The transfer rate of data can go upto 1Mbps (Mega-byte per second).
11. Which sensor should be used for calculating pressure?
a) DHT11
b) LM335Z/NOPB
c) HC-SR04
d) MPX10DP

Answer: d
Explanation: MPX10DP sensor should be used for calculating pressure. MPX10DP is a pressure sensor which can
measure pressure up to 10 kPa. HC-SR04 is an example of Ultrasonic Sensor. LM335Z/NOPB is temperature
sensor. DHT11 is a temperature and humidity sensor.

12. Which sensor should be used for calculating humidity?

a) DHT11
b) LM335Z/NOPB
c) HC-SR04
d) MPX10DP

Answer: a
Explanation: DHT11 sensor should be used for calculating humidity. It can also be used as temperature sensor.
MPX10DP is a pressure sensor which can measure pressure up to 10 kPa. HC-SR04 is an example of Ultrasonic
Sensor. LM335Z/NOPB is temperature sensor.

13. Which sensor should be used for calculating distance?

a) DHT11
b) LM335Z/NOPB
c) HC-SR04
d) MPX10DP

Answer: c
Explanation: HC-SR04 sensor should be used for calculating distance. HC-SR04 is a Ultrasonic Sensor that has a
range of 13 feet linearly. MPX10DP is a pressure sensor which can measure pressure up to 10 kPa. LM335Z/NOPB
is temperature sensor. DHT11 is a temperature and humidity sensor.
14. Which sensor should be used for calculating temperature as well as humidity?
a) DHT11
b) LM335Z/NOPB
c) HC-SR04
d) MPX10DP

Answer: a
Explanation: DHT11 sensor should be used for calculating temperature as well as humidity. MPX10DP is a pressure
sensor which can measure pressure up to 10 kPa. HC-SR04 is an example of Ultrasonic Sensor. LM335Z/NOPB is
temperature sensor but it cannot calculate humidity.

15. Which sensor is used in line following robots?

a) Infrared Sensor
b) Microwave Radar Sensor
c) Ultrasonic Sensor
d) Temperature Sensor

Answer: a
Explanation: Infrared Sensor is used in line following robots. These line following robots follow a path which is made
by black strips or tapes. These robots use a bunch of infrared sensors which makes them work accurately.