1.Which of the following is not a characteristic of an ideal transducer?

a) High dynamic range

b) Low linearity
c) High repeatability
d) Low noise

Answer: b
Explanation: An ideal transducer should show high linearity. A linear system should
produce exact output according to input.

2.A transducer converting ground movement or velocity to voltage is known as

________________
a) Geophone
b) Pickup
c) Hydrophone
d) Sonar transponder

Answer: a
Explanation: Geophone is a device used to convert ground movement to voltage, which
is used in Remote ground sensors (RGS) and also as a replacement for broadband
seismometers.

3.Which of the following represent active transducer?

a) Strain gauge
b) Thermistor
c) LVDT
d) Thermocouple

Answer: d
Explanation: Active transducers are self-generating type; they don’t require external
power to work while passive transducers require external power to work.

4. Which transducer is known as ‘self-generating transducer’?

a) Active transducer
b) Passive transducer
c) Secondary transducer
d) Analog transducer

Answer: a
Explanation: The name self-generating transducer is due to its property of working
without the use of external power

5. What is the relation between scale factor and sensitivity of a transducer?

a) Scale factor is double of sensitivity
b) Scale factor is inverse of sensitivity
c) Sensitivity is inverse of scale factor
d) Sensitivity is equal to scale factor

Transfer Function :

It is defined as the ratio of output quantity of a transducer to input quantity of that

transducer and is given by,

Where, qo is the output of the transducer and qi is the input of the transducer. The
Sensitivity is given by,

Generally, the sensitivity is not constant and depends on qi. But, in some cases, a linear
relation exists between qo and qi. In those cases, the sensitivity will be constant
throughout the range of the transducer. The inverse of sensitivity is known as the scale
factor (i.e., dqi/dqo).
6. Which of the following is an analog transducer?
a) Encoders
b) Strain gauge
c) Digital tachometers
d) Limit switches

Answer: b
Explanation: Analog transducers convert physical quantity to analog signals while digital
transducers convert physical quantity to digital signals. Strain gauge is an example of
an Analog transducer.
7. What is the principle of operation of LVDT?
a) Mutual inductance
b) Self-inductance
c) Permanence
d) Reluctance

Answer: a
Explanation: Linear variable differential transformer (LVDT) is a type of transformer
used for measuring displacement, and it has the same principle of operation of
transformer.
8. Which of the following can be measured using Piezo-electric transducer?
a) Velocity
b) Displacement
c) Force
d) Sound

Answer: c
Explanation: Piezo-electric crystals produces an electric signal when pressure applied.
Examples are quartz, Rochelle salt. That is, it converts force into electric signals.
9. Capacitive transducer is used for?
a) Static measurement
b) Dynamic measurement
c) Transient measurement
d) both static and dynamic

Answer: b
Explanation: Capacitive transducers convert measurant into changes in capacitance.
Change in capacitance is caused by change in dielectric or change in distance between
plates.
10. Which of the following is used in photo conductive cell?
a) Selenium
b) Quartz
c) Rochelle salt
d) Lithium sulphate

Answer: a
Explanation: Photo conductive action is the property of reduction of resistance when
exposed to light. Selenium shows photoconductive action.

11.Closeness of measured value to true value is _________________

a) Accuracy
b) Precision
c) Correction
d) Uncertainty

Answer: a
Explanation: Accuracy of a measurement is defined by closeness of a measured value
to true value.

12. _______________ of a measuring system refers to its ability to follow instant by

instant the measurand with time.
a) Bandwidth
b) Fidelity
c) Measurement lag
d) Settling time

Answer: b
Explanation: Fidelity of a measuring system or transducer refers to its ability to follow
instant by instant the variations of measurand with time.

13. For a measuring system, dynamic sensitivity is required to be ________ of static

sensitivity.
a) ±2%
b) ±5%
c) ±10%
d) ±20%

Answer: a
Explanation: For a measuring system, tolerated variation of dynamic sensitivity is only
±2% of static sensitivity. That is dynamic sensitivity should be minimum.

14. What is ‘live zero’?

a) Output zero for zero input
b) Output non zero for zero input
c) Output null for all input
d) Output unpredictable

Answer: b
Explanation: Live zero is a term used to describe a system in which output has a
nonzero value for zero input.

15. Inductive potentiometers are used to measure ________________

a) Voltage
b) Current
c) Displacement
d) None of the mentioned

Answer: c
Explanation: It has same function as linear potentiometers and is used for measuring
displacement.

16. Process of physical deformation on application of electric field is described by

___________
a) Electromagnetic property
b) Electro mechanical property
c) Magnetostriction property
d) Electrostriction property

Answer: d
Explanation: Electrostriction property is defined by physical deformation of certain
materials on the application of electrical field

17. Who invented the piezoelectric effect?

a) Mary Elizabeth Barber
b) Christian Doppler
c) Marie curie and Pierre curie
d) Pierre curie and Jacques curie.

Answer: d
Explanation: Piezoelectric effect was first invented and explained by curie brothers,
Pierre curie and Jacques curie in 1980.

18. Which of the following represents piezoelectric materials?

a) ADP
b) Quartz
c) Bernilite
d) All of the mentioned

Answer: d
Explanation: Quartz, ADP (Ammonium dihydrogen Phosphate), and bernilite are
examples of piezoelectric materials.

19. Which of the following quantities cannot be measured using piezoelectric

transducers?
a) Pressure
b) Strain
c) Acceleration
d) None of the mentioned

Answer: d
Explanation: Piezoelectric transducers can be used to measure a wide range of
quantities like pressure, acceleration, strain displacement etc.

20. In piezoelectric strain transducer voltage developed is _______________ to strain

applied.
a) Directly proportional
b) Inversely proportional
c) Equal
d) Independent
Answer: a
Explanation: For a piezoelectric strain transducer, as the strain applied increases output
voltage also increases.

21. Identify most suitable definition of a transducer.

a) A transducer is a device that converts energy from one form to another.

b) Transducer is a device which converts mechanical energy into electrical energy.

c) A Transducer is a device which converts electrical energy into mechanical energy.

d) Transducer is a device which converts physical quantity into electrical quantity.

Option 1: A transducer is a device that converts energy from one form to another.

22. _________is a self-generating type transducer that can produce an electrical voltage
or current output without utilizing any external power source.

a) A passive transducer

b) An active transducer

c) A primary transducer

d) A secondary transducer

Option 2: An active transducer

23.The transducer which needs an external power supply for its operation is
called________.

a) Active Transducer

b) Passive Transducer

c) Inactive Transducer

d) Capacitive Transducer

Option 2: Passive Transducer

24 Which of the following is not a passive transducer?

a) LVDT

b) LDR
 c) Strain gauge

d) Thermocouple

Option 4: Thermocouple

25 An electrical transducer _________.

a) requires external power for conversion of one quantity into other.

b) does not require external power for conversion of one quantity into other.

c) converts any quantity to be measured into a usable electrical signal.

d) converts electrical signals into pressure.

Option 3: converts any quantity to be measured into a usable electrical signal.

26 In case of pressure measurement, bourdon tube is a primary sensor which converts

pressure first into displacement, and then the displacement is converted into an output
voltage by an LVDT. In this case LVDT is ________.

a) primary transducer

b) secondary transducer

c) electrical transducer

d) pre-primary transducer

Option 2: secondary transducer

27 Transducers, on the basis of nature of output signal, may be classified into

a) primary and secondary transducers

b) active and passive transducers

c) electrical and inverse transducers

d) analog and digital transducers

Option 4: analog and digital transducers

28. Optical radiations involve _________

a) optoelectric devices
b) biological devices
c) mechanical devices
d) chemical devices

Answer: a
Explanation: Emission and absorption of optical radiations are carried out by making
use of optoelectric devices.

29 Photoelectric transducers consist of _______

a) 1 transducer
b) 3 transducers
c) 5 transducers
d) 10 transducers

Answer: b
Explanation: A photoelectric transducer consists of 3 transducers. They are as follows:
Photo-emissive
Photo-conductive
Photo-voltaic.

30 Photoconductive transducers produce output ________

a) due to change in inductance
b) due to change in light
c) due to change in resistance
d) due to change in temperature

Answer: c
Explanation: A photoconductive transducer produces an output due to a change in the
resistance. Electrical output is produced due to a variation in the temperature.

31 Commonly used photoemissive material is _______

a) gold
b) opium
c) tellurium
d) cesium-antimony

Answer: d
Explanation: Cesium-antimony is the most commonly used photoemissive material. The
photoemissive material is housed in a glass tube. Photoemissive devices are also
called as phototubes.

32 Photoconductors are made of _______

a) thick layer of semiconductor
b) thin layer of semiconductor
c) capacitive substrate
d) inductive substrate

Answer: b
Explanation: Photoconductors comprise of a thin layer of semiconductor.
Photoconductors not consisting of a junction are known as junction less detectors.

33 . Piezoelectric transducer is used for measuring __________

a) non-electrical quantities
b) electrical quantities
c) chemical quantities
d) any quantity

Answer: a
Explanation: A piezoelectric transducer is used for measuring non-electrical quantities
such as vibration, acceleration, pressure and the intensity of sound.

34 Piezoelectric crystals __________

a) float on water
b) dissolve in water
c) are not soluble in water
d) absorb water

Answer: b
Explanation: A piezoelectric crystal dissolves in water. It is fully soluble in water. When
the temperature is humid, the piezoelectric crystals gets dissolved in water.

35 Piezoelectric crystals produce _________

a) no voltage
b) low voltage
c) high voltage
d) very high voltage

Answer: c
Explanation: Piezoelectric crystals can be used spark ignition engines. They are also
used in electrostatic dust filters and produce high voltage at low current.

36 Piezoelectric transducer consists of _________

a) copper rod
b) aluminum wire
c) gold crystal
d) quartz crystal

Answer: d
Explanation: A piezoelectric transducer consists of a quartz crystal. It comprises of
silicon and oxygen arranged in a crystal structure of SiO2.

37When a compressive force is applied to a quartz crystal then ____________

a) positive charges are induced
b) negative charges are induced
c) no charge is induced
d) both positive and negative charges are induced

Answer: a
Explanation: When a quartz crystal is subjected to compressive stress, positive charges
are induced in one side of the crystal while negative charges are induced on the other
side of the crystal.

38 In kitchen applications a piezoelectric crystal is used for _________

a) skimming milk
b) lighting a gas stove
c) grinding
d) mixing

Answer: b
Explanation: A piezoelectric lighter is used for lighting a gas based stove in kitchen
applications. The pressure induced on the piezoelectric sensor creates an electric
signal leading to a spark.

39 A piezoelectric transducer has a _________

a) very high sensitivity
b) low sensitivity
c) high sensitivity
d) zero sensitivity

Answer: c
Explanation: The sensitivity is high in a piezoelectric transducer. A piezoelectric
transducer can be used as a sensor. It can also be used in an accelerometer due to its
good frequency response.

40 A piezoelectric transducer is used as an ignition source for a cigarette.

a) True
b) False

Answer: a
Explanation: Cigarettes use piezoelectric transducers as a source of ignition. They are
also used in the measurement of sonar, microphone, pressure, displacement and force.

41 Microphone converts light into heat.

a) True
b) False

Answer: b
Explanation: A microphone is used to convert the pressure induced in the form of sound
waves into electric signal. The electrical signal is then amplified to produce louder
sound.

42 A quartz crystal is _________

a) a chemical transducer
b) a photoelectric transducer
c) not a self-generating transducer
d) a self-generating transducer

Answer: d
Explanation: The quartz crystal is a self-generating transducer. It does not need any
electric voltage for operation. The quartz crystal becomes short in length due to an
applied electric field in the opposite direction.

43 Mutual inductance between two coils is given as _________

a) M = kL1L2−−−−√
b) M = kL1−−√
c) M = kL2−−√
d) M = L1L2−−−−√

Answer: a
Explanation: The mutual inductance between two coils is given by the relation
M = kL1L2−−−−√
where, k is the coefficient of coupling
M is the mutual inductance between the coils.

44 Mutual inductance depends on _________

a) self-inductance
b) self-inductance and coefficient of coupling
c) coefficient of coupling
d) permittivity of air

Answer: b
Explanation: The mutual inductance of a pair of coils depends on the self-inductance of
the individual coils and on the coefficient of coupling.

45. Self-inductance of an inductor is given by ________

a) L = N⁄S
 1
b) L = ⁄S
N2
c) L = ⁄S
2
d) L = N

Answer: c
Explanation: The self-inductance of an inductor is obtained by making use of the
relation
L = N2⁄S
where, N is the number of coil
S is the reluctance of the coil (A/Wb).

46 Reluctance of a coil is given by which of the following relation?

a) S = 1⁄A
b) S = 1⁄μ
c) S = a⁄μA
d) S = 1⁄μA

Answer: d
Explanation: The reluctance of an inductance coil is given by the relation
S = 1⁄μA
where, l is the length of the magnetic circuit (m)
a is the area of the magnetic circuit which encloses the flux (m2)
µ is the permeability of the core (H/m).

47 Self-inductance depends on ________

a) permeability
b) permittivity
c) plank’s constant
d) rydberg constant

Answer: a
Explanation: The self-inductance of an inductor is obtained by making use of the
relation
L = N2⁄S
where, N is the number of coil
S is the reluctance of the coil (A/Wb)
As reluctance depends on the permeability, the self-inductance of a coil depends on the
permeability.

48What is the relation between the self-inductance and the reluctance of a coil?
a) directly proportional
b) inversely proportional
c) no relation
d) constant

Answer: b
Explanation: The self-inductance of an inductor is obtained by making use of the
relation
L = N2⁄S
where, N is the number of coil
S is the reluctance of the coil (A/Wb)
We observe from the above equation that the self-inductance of a coil is inversely
proportional to its reluctance.

49 Based on self-inductance of a coil, how many types of inductive transducers are

available?
a) 5
b) 10
c) 4
d) 20

Answer: c
Explanation: Based on the self-inductance of an inductive coil, there are four types of
inductive transducers available. They are as follows:
i) Variable permeability inductive transducer
ii) Variable reluctance inductive transducer
iii) Eddy current inductive transducer
iv) Linear variable differential transducer.

50 In an eddy current transducer output depends on the variation in the eddy current.
a) True
b) False

Answer: a
Explanation: An eddy current transducer is a self-generating type of inductive transducer.
In an eddy current transducer, output depends on the change in the value of the eddy
current at the input.

51 An inductive transducer measures the variation in ________

a) reluctance
b) resistance
c) capacitance
d) self-inductance

Answer: d
Explanation: Inductive transducer measures the variation in the self-inductance and
mutual inductance of an inductive coil. Variation in the inductance is measured as a
change in the displacement.

52 Which of the following represents the correct expression of Lorentz force?

a) EH/b
b) eEH/b
c) eEH
d) None of the mentioned

Answer: b
Explanation: Magnitude of Lorentz force will be equal to the ratio of the product of
electronic charge and Hall potential with width in meters.

53 Hall potential is inversely proportional to magnetic flux density.

a) True
b) False

Answer: b
Explanation: Hall potential is always directly proportional to magnetic flux density.
Expression is given as EH=BbV; where b is the width and V represents velocity

54 Hall Effect is clearly visible in _______________

a) Pure conductors
b) Semiconductors
c) Super conductors
d) Metals

Answer: b
Explanation: Hall coefficient depends on the number of free charge carriers and it is
clearly visible in semiconductors.

55Force exerted by magnetic field in Hall Effect transducers is ____________

a) Lorentz force
b) Hall Effect force
c) Magnetic force
d) Electric force

Answer: a
Explanation: Lorentz force is the force exerted by a magnetic field in Hall Effect
transducers. On equilibrium condition Lorentz force balances Hall Effect force.

56 Which of the following represents the output of Hall Effect transducer?

a) Hall potential
b) Emf
c) Applied voltage
d) Lorentz Voltage

Answer: a
Explanation: Output of Hall Effect transducer is called Hall potential and is denoted by
EH.

57 Hall Effect transducer can be used to measure ___________

a) Magnetic field
b) Angular displacement
c) Linear displacement
d) All of the mentioned

Answer: d
Explanation: Hall Effect transducers can be used to measure linear and angular
displacement and magnetic field etc.

58 Which of the following conversion take place in bourdon tubes?

a) Pressure to displacement
b) Pressure to voltage
c) Pressure to strain
d) Pressure to force

Answer: a
Explanation: In bourdon tubes converts input pressure into displacement and
displacement of the needle will be directly proportional to input pressure.

59 Full form of LVDT is

a) Linear Variable Differential Transducer

b) Line Voltage Differential Transformer

c) Linear Variable Differential Transformer

d) Line Voltage Differential Transducer

Option 3: Linear Variable Differential Transformer

60 Which of the following quantity can be directly measured by LVDT?

a) Displacement

b) Force

c) Pressure
 d) Weight

Option 1: Displacement

LVDT can dirctly measure displacement. Further, this displacement can be used to
measure pressure, weight, force and velocity.

61 LVDT is ______ type of transducer.

a) Resistive

b) Capacitive

c) Inductive

d) Optical

Option 3: Inductive

Explanation: Because LVDT has core and winding. The principle of working of LVDT is
same as that of transformer. Therefore, change in induced e.m.f. is measured in it.

62 An AC LVDT has ___ input and ___ output.

a) AC, DC

b) DC, AC

c) AC, AC

d) DC, DC

Option 3: AC, Ac

63The LVDT has

a) one primary and two secondary windings.

b) two primary and one secondary winding.

c) one primary and one secondary winding.

d) two primary and four secondary windings.

Option 1: one primary and two secondary windings.

64 Thermoelectric transducer is a __________
a) temperature transducer
b) pressure transducer
c) inductive transducer
d) capacitive transducer

Answer: a
Explanation: A thermoelectric transducer is a temperature transducer. It converts
thermal energy into electrical energy.

65 Commonly used thermoelectric transducer is __________

a) thermometer
b) thermocouple
c) linear variable differential transducer
d) loud speaker

Answer: b
Explanation: The most commonly used thermoelectric transducer is a thermocouple. It
measures the change in temperature and converts it into an electrical signal.

66. The algebraic sum of e.m.f.s in a circuit containing thermocouples is __________

a) infinite
b) hundred
c) zero
d) ten

Answer: c
Explanation: In a circuit consisting of many thermocouples, the algebraic sum of the
e.m.f.s produced is zero. It remains constant with temperature.

67 What is a thermopile?
a) single thermocouple
b) series-parallel connection of thermocouples
c) parallel connection of thermocouples
d) series of thermocouples

Answer: d
Explanation: Thermopile is a series connection of thermocouples. By making use of
thermopiles, a more sensitive element is obtained as compared to a single
thermocouple.

68 Most suitable material for a thermocouple is ________

a) brass
b) gold
c) platinum
d) silver

Answer: c
Explanation: Platinum is the most suitable material for constructing thermocouples. It
has a very high sensitivity. Constantan is the other material (alloy) with a composition of
40 % of Ni and 60 % of Cu used in a thermocouple.

69 If two different metals are joined forming a closed circuit an electric current flows.
a) True
b) False

Answer: b
Explanation: When two different metals are joined together forming a closed circuit, if
the temperatures of the two junctions are different then an electric current flows
through the circuit.

70 Operation of thermocouple is governed by _______________

a) Peltier effect
b) Seebeck effect
c) Thomson effect
d) All of the mentioned

Answer: d
Explanation: Operation of thermocouple is based on three major effects- Peltier,
Thomson and seebeck, all describe the relation between current flow and temperature
between two different metal.

71 . ______________ describes current flow between two junctions formed by two

different metals.
a) Peltier effect
b) Thomson effect
c) Seebeck effect
d) None of the mentioned

Answer: a
Explanation: When two different metals are connected to form two junctions, current
flow will occur from one junction to other. This is described by peltier effect.

72. A Semiconductor PN Junction device which converts light energy into ________
energy.

a) Mechanical
 b) Electrical

c) Heat

d) Sound

Ans b

73. Photodiode used (Operate) in reverse bias.

a) True

b) False

Ans True

74 According to the quantum theory, light consists of small energy packets which are
called ________.

a) Proton

b) Photon

c) krypton

d) All are correct

Ans b

75 . When there is no incident light, the reverse current in a photodiode is essentially

non-existent and is referred to as

a) Zener current

b) Dark current

c) Photocurrent

d) PIN current

Answer: 2) Dark current

When there is no incident light, the reverse current, also known as the dark current, is
almost non-existent. When the amount of light intensity is increased, the reverse current
increases as well.

76 The LED emits light when it is

a) reverse biassed
b) unbiassed
c) forward biassed
d) none of these

Ans: 3) forward biassed

A light emitting diode (LED) is a light-emitting device. When the LED is forward biassed,
it produces light; when it is reverse biassed, it produces no light. The square of the
current flowing through the gadget determines the intensity of light.

77 The LED works on the principle of

a) fluorescence
b) hall effect
c) electroluminescence
d) none of these
Ans: 3) electroluminescence

78 A light-emitting diode (LED) produces light when current travels through it. Electrons
recombine with electron holes in the semiconductor, producing energy in the form of
photons.

78 The unit of intensity of light is

a) Lm/A
b) Lm/W
c) Lm/w2
d) Lm/m2

Ans: 4) Lm/m2

Light intensity is measured in lumens per square metre or lux, while light output is
measured in lumens

79 Accuracy is defined as the closeness that a reading approaches with respect to a

standard value.
a) True
b) False

Answer: a
Explanation: Accuracy in the measurement of a quantity is defined as the closeness
that a reading approaches when it measured with a standard value.

80 The output of a transducer must ___________

a) be different at different environment conditions
b) be same at all environment conditions
c) be same at some environment conditions
d) be zero always

Answer: b
Explanation: Output of a transducer must be the same under various environmental
conditions when same input is applied to it.

81. The output of a transducer must be __________

a) low
b) medium
c) high
d) zero

Answer: c
Explanation: Output of a transducer is usually high so that it can be easily measured and
processed. The transducer output is generally higher than the noise. As a result most of
the application makes use of digital outputs.

82. The size of a transducer must be __________

a) infinite
b) zero
c) large
d) small

Answer: d
Explanation: A transducer generally has a small size and shape. It occupies minimum
volume and has a minimum weight. As a result the system being measured will become
compact.

83. 5. A transducer must be __________

a) quick in response
b) slow in response
c) medium in response
d) very slow in response

Answer: a
Explanation: The transducer is generally fast in response. Speed of response basically
tells the time taken by the transducer to produce the output in a fast and efficient
manner.

84. The output of a transducer must __________

a) be less reliable
b) be highly reliable
c) not be reliable
d) be of medium reliability

Answer: b
Explanation: Output of a transducer is generally high in reliability. Changes in the
environment conditions should not affect the output of a transducer.

85. The range of a transducer is __________

a) medium
b) narrow
c) large
d) zero

Answer: c
Explanation: A transducer has a large range of operation. The operating range is set
wide so that it is useful for a wide range of operating frequencies.

86. The transducer output is __________

a) exponential
b) unit step
c) non-linear
d) linear

Answer: d
Explanation: Transducer output varies linearly with the input quantity that is being
measured. A transducer must have a linear input vs output characteristic response.

87. The sensitivity of an electrical transducer is obtained by dividing the electrical

output with respect to a unit change in the physical quantity.
a) True
b) False

Answer: a
Explanation: Sensitivity of an electrical transducer is defined as the ratio of the electrical
output to a unit change in the value of a physical quantity such as temperature, pressure,
etc.

88. A battery is an arrangement of electrolytic cells.

a) True
b) False

Answer: b
Explanation: A battery is not an arrangement of electrolytic cells, but an arrangement of
electrochemical cells. An electrochemical cell is one which converts chemical energy
into electrical energy whereas an electrolytic cell is one which converts electrical energy
into chemical energy. Since batteries convert chemical energy to electrical energy, it is
an arrangement of electrochemical cells.

89. Which of the following is not a requirement for a useful battery?

a) It should be light and compact
b) It should have a reasonable life span
c) It should ideally have a constant voltage throughout its lifespan
d) It should supply Alternating Current(AC)

Answer: d
Explanation: A useful battery is expected to be light and compact to be easily
transported. It is expected to have a reasonable lifespan to justify its usage. Its voltage
should not vary appreciably during usage so that it doesn’t adversely affect the circuit it
is used in. A battery supplies Direct Current(DC) and not Alternating Current(AC).

90. Which of the following statements is true regarding a primary cell?

a) The electrode reactions can be reversed
b) It can be recharged
c) An example of a primary cell is a mercury cell
d) An example of a primary cell is a nickel-cadmium storage cell

Answer: c
Explanation: A primary cell is one in which the electrode reactions occur only once and
cannot be reversed by applying electrical energy. Therefore, primary cells cannot be
recharged. A mercury cell is an example of a primary cell, whereas a nickel-cadmium
storage cell is an example of a secondary cell.

91Secondary cells are also called storage cells.

a) True
b) False

Answer: a
Explanation: Secondary cells are those cells in which the electrode reaction can be
reversed by applying an electrical energy. Therefore, they can be used to store electrical
energy. So, they are also known as storage cells.

92. Which of the following is used as an anode in a dry cell?

a) Zinc
b) Graphite
c) Mercury(II) oxide
d) Nickel
Answer: a
Explanation: A dry cell is constructed using zinc and graphite. It consists of a zinc
cylinder through whose centre passes a graphite rod. The zinc cylinder acts as an anode,
whereas the graphite rod acts as a cathode.

93. Which of the following is the electrolyte used in a dry cell?

a) Ammonium chloride
b) Manganese dioxide
c) Potassium hydroxide
d) Sulphuric acid

Answer: a
Explanation: The electrolyte in a dry cell is ammonium chloride in the form of a moist
paste placed next to the zinc anode. In some dry cells marketed as “heavy-duty”, the
ammonium chloride is replaced by zinc chloride.

94What is the role of manganese dioxide in a dry cell?

a) It acts as an electrolyte
b) It acts as the cathode
c) It acts as an anode
d) It acts as a depolarizer

Answer: d
Explanation: In a dry cell, in the remaining space between the electrolyte and the
graphite cathode, a second paste consisting of ammonium chloride and manganese
dioxide is applied. The manganese dioxide acts as a depolariser as it helps to prevent
the build-up of hydrogen gas bubbles.

95. Which of the following is the voltage output of a mercury cell?

a) 1.55V
b) 1.35V
c) 2.55V
d) 1V

Answer: b
Explanation: Mercury batteries use a reaction between mercuric oxide and zinc in an
alkaline electrolyte to produce electricity. Its voltage during discharge is a constant
1.35V.

96. Which of the following statements is not true with respect to a lead storage cell (or
a lead-acid battery)?
a) The electrolyte used is an aqueous solution of sulphuric acid
b) The anode is made up of lead
c) The cathode is made up of lead(IV) oxide
d) It is a primary cell

Answer: d
Explanation: A lead storage cell is a secondary cell which has a grid of lead packed with
finely divided spongy lead for an anode and a grid of lead packed with lead(IV) oxide for
a cathode. The electrolytic solution used in a lead-acid battery is an aqueous solution of
sulphuric acid.

97. Which of the following products are formed when a lead storage battery is
discharged?
a) SO2
b) Pb
c) PbO2
d) PbSO4

Answer: d
Explanation: During the working of the lead storage battery, PbSO4 is formed at both the
electrodes and sulphuric acid is used up. At the anode, Pb is oxidised to form
PbSO4 and at the cathode, PbO2 is reduced to form PbSO4.

98. What will be the grouping of cells when the current in the circuit is ne(R+nr)?
a) Parallel grouping
b) Series grouping
c) Mixed grouping
d) When there is no grouping

Answer: b
Explanation: When n identical cells, each of emf ‘e’ and internal resistance ‘r’ are
connected to the external resistance ‘R’ in series, its called series grouping. In series
grouping eeq = ne and req = nr Therefore, current in the circuit (I) = ne(R+nr).

99. In parallel grouping of cells, we obtain more current.

a) True
b) False

Answer: a
Explanation: Yes, in parallel grouping of cells, we obtain more current. In parallel
combination, the voltage remains the same and the resistance offered is minimum. As
more cells are added parallel to each other, then the resistance will keep reducing. As a
result, more current can be obtained.

100. The capacity of a battery is expressed in terms of

 A. Current rating

B. Voltage rating

C. Ampere hour rating

D. None of the above

Ans C. Ampere hour rating

101The storage battery generally used in electric power station is

A. Nickel-cadmium battery

B. Zinc carbon battery

C. Lead-acid battery

D. None of the above

ansC. Lead-acid battery

102Trickle charger of a storage battery helps to

A. Maintain proper electrolyte level

B. Increase its reverse capacity

C. Prevent sulphation

D. Keep it fresh and fully charged

Ans.D. Keep it fresh and fully charged

A trickle chargers' primary purpose is to slowly charge a battery and prevent

overcharging. This small current charging is known as Trickle charging. Trickle
charging keeps the battery always fully charged and in ready to use condition, ..

103Earthing is necessary to give protection against

 A. Danger of electric shock

B. Voltage fluctuation

C. Overloading

D. High temperature of the conductors

A. Danger of electric shock

104 The unit of solid angle is

A) steradian
B) candela
C) radian
D) solid angle.

Ans : (A)

105Luminous efficiency of a fluorescent tube is

A) 5 - 10 lumen/watt
B) 15 - 20 lumen/watt
C) 30 - 40 lumen/watt
D) 60 - 65 lumen/watt.

Ans : (D)

One lumen per square meter is the same as

A) One lux
B) One candela
C) One foot candle
D) One lumen meter.

Ans : (A)
Candela is the unit of
A) Luminous intensity
B) Luminous flux
C) Wavelength
D) None of the above.

Ans : (A)

The illumination is directly proportional to the cosine of the angle made by the normal to
the illuminated surface with the direction of the incident flux. Above statement is
associated with
A) Planck’s law
B) Macbeth’s law of illumination
C) Bunsen’s law of illumination
D) Lambert,s cosine law.

Ans : (D)

Light is produced in electric discharge lamps by

A) carbon electrodes
B) ionization in a gas or vapour
C) magnetic effect of current
D) heating effect of current.

Ans : (B)

The capacitor used in auto transformer circuit for sodium vapour lamps, is for
A) protection against accidental power failure
B) controlling illumination level of the lamp
C) for regulating discharge voltage
D) for improving the power factor of the circuit.
Ans : (D)

A mercury vapour lamp gives

A) pink light
B) yellow light
C) greenish blue light
D) white light.

Ans : (C)

Lumen/watt is the unit of

A) Luminous efficiency
B) Brightness
C) Luminous intensity
D) Light flux.

Ans : (A)

Which of the following electric discharge lamp gives highest lumens/watt

A) Neon lamp
B) Sodium vapour lamp
C) Mercury lamp at low pressure
D) Mercury vapour at high pressure.

Ans : (B)

Which gas is sometimes used in filament lamps ?

A) Carbon dioxide
B) Nitrogen
C) Krypton
D) Argon.

Ans : (D)

The output of a tungsten filament lamp depends on

A) size of lamp
B) size of shell
C) temperature of filament
D) all of the above.

Ans : (C)

Melting temperature of tungsten is

A) 3655o K
B) 2655o K
C) 2500o K
D) 2000o K.

Ans : (A)

The flicker effect of fluorescent lamps is more pronounced at

A) lower voltages
B) higher voltages
C) lower frequencies
D) higher frequencies.

Ans : (C)

The life incandescent lamp is expected to be

A) 100 hours
B) 200 hours
C) 1000 hours
D) 10000 hours.
Ans : (C)

One Angstrom is
A) 10-6meter
B) 10-8 meter
C) 10-8 cm
D) 10-8 mm.

Ans : (C)

The purpose of providing a choke in tube light is

A) to eliminate corona effects
B) to avoid radio interference
C) to improve power factor
D) to limit current to appropriate value.

Ans : (D)

A 60 W lamp given a luminous flux of 1500 lumen. Its efficiency is

A) 2.5 lumen/watt
B) 25 lumen/watt
C) 250 lumen/watt
D) 1500 lumen/watt.

Ans : (B)