)

Section 1: Ohm’s Law

1. Ohm's Law is defined as: a) V = I/R b) V = IR c) I = VR d) R = VI

Answer: b
2. The unit of resistance is: a) Ampere
b) Volt
c) Ohm
d) Watt
Answer: c
3. If V = 12V and R = 4 ohms, what is the current?
a) 2 A
b) 3 A
c) 4 A
d) 6 A
Answer: b
4. Resistance is directly proportional to:
a) Voltage
b) Current
c) Power
d) Length
Answer: d
5. Ohm’s Law is not applicable for: a) Conductors
b) Non-linear devices
c) Resistors
d) Metallic wires
Answer: b

Section 2: Kirchhoff’s Laws

6. KCL is based on: a) Conservation of mass

b) Conservation of charge
c) Conservation of energy
d) None of the above
Answer: b
7. The sum of voltages in a closed loop is: a) Infinite
b) Zero
c) One
d) Equal to power
Answer: b
8. KVL deals with: a) Currents at node
b) Voltages in a loop
c) Charges in capacitor
d) Resistance calculation
Answer: b
9. KCL is applicable at: a) Branch
b) Node
c) Loop
 d) Mesh
Answer: b
10. In Kirchhoff’s laws, passive sign convention is: a) Always necessary
b) Never followed
c) Optional
d) None of the above
Answer: a

Section 1: Ohm’s Law

1. Ohm's Law is defined as: a) V = I/R b) V = IR c) I = VR d) R = VI

Answer: b
2. The unit of resistance is: a) Ampere
b) Volt
c) Ohm
d) Watt
Answer: c
3. If V = 12V and R = 4 ohms, what is the current?
a) 2 A
b) 3 A
c) 4 A
d) 6 A
Answer: b
4. Resistance is directly proportional to:
a) Voltage
b) Current
c) Power
d) Length
Answer: d
5. Ohm’s Law is not applicable for: a) Conductors
b) Non-linear devices
c) Resistors
d) Metallic wires
Answer: b

Section 2: Kirchhoff’s Laws

6. KCL is based on: a) Conservation of mass

b) Conservation of charge
c) Conservation of energy
d) None of the above
Answer: b
7. The sum of voltages in a closed loop is: a) Infinite
b) Zero
c) One
d) Equal to power
Answer: b
8. KVL deals with: a) Currents at node
b) Voltages in a loop
c) Charges in capacitor
 d) Resistance calculation
Answer: b
9. KCL is applicable at: a) Branch
b) Node
c) Loop
d) Mesh
Answer: b
10. In Kirchhoff’s laws, passive sign convention is: a) Always necessary
b) Never followed
c) Optional
d) None of the above
Answer: a

Section 3: Voltage and Current Division Rules

11. Voltage division rule applies to: a) Series circuits

b) Parallel circuits
c) Short circuits
d) Complex circuits
Answer: a
12. Current division rule applies to: a) Series circuits
b) Parallel circuits
c) Short circuits
d) Open circuits
Answer: b
13. In a series circuit, the voltage is divided: a) Equally
b) According to resistance
c) By current
d) Randomly
Answer: b
14. In a parallel circuit, the current divides: a) Equally
b) According to resistance
c) Randomly
d) According to voltage
Answer: b
15. Voltage division in two resistors R1 and R2 in series: a) V1 = (R2 / (R1 + R2)) * V
b) V1 = (R1 / (R1 + R2)) * V
c) V1 = R1 * V
d) V1 = V / R1
Answer: b

Section 4: Basics of Semiconductors

16. Intrinsic semiconductors are: a) Pure semiconductors

b) Doped semiconductors
c) Conductors
d) Insulators
Answer: a
17. Doping is: a) Making semiconductors pure
b) Adding impurities to a semiconductor
 c) Removing electrons
d) None of the above
Answer: b
18. N-type semiconductors have: a) More holes
b) More electrons
c) Equal electrons and holes
d) No charge carriers
Answer: b
19. P-type semiconductors are doped with: a) Pentavalent atoms
b) Trivalent atoms
c) Tetravalent atoms
d) None
Answer: b
20. The majority carriers in N-type are: a) Holes
b) Electrons
c) Neutrons
d) Ions
Answer: b

Section 5: PN Junction Diode

21. A PN junction is formed by: a) Joining two metals

b) Joining P and N type semiconductors
c) Joining two insulators
d) None of the above
Answer: b
22. The PN junction diode conducts current in: a) Forward bias
b) Reverse bias
c) No bias
d) Both directions equally
Answer: a
23. The barrier potential for silicon diode is: a) 0.3 V
b) 0.7 V
c) 1.0 V
d) 1.5 V
Answer: b
24. Reverse bias means: a) P connected to +ve
b) N connected to +ve
c) No current flows
d) Short circuit
Answer: b
25. A diode can be used as a: a) Switch
b) Amplifier
c) Filter
d) Oscillator
Answer: a

Section 6: Applications of Diodes

 26. Rectifiers convert: a) AC to DC
b) DC to AC
c) Voltage to current
d) High voltage to low
Answer: a
27. Half wave rectifier efficiency is: a) 100%
b) 81.2%
c) 40.6%
d) 50%
Answer: c
28. In a full-wave rectifier: a) Only negative half passes
b) Both halves pass
c) No current flows
d) Output is AC
Answer: b
29. Zener diode is used for: a) Amplification
b) Oscillation
c) Voltage regulation
d) Signal mixing
Answer: c
30. Clipping circuit removes: a) Lower half
b) Upper half
c) Part of waveform
d) All of above
Answer: d

Section 7: Bipolar Junction Transistor (BJT)

31. BJT is: a) Unipolar device

b) Bipolar device
c) Linear device
d) Passive device
Answer: b
32. BJT terminals are: a) Source, Drain, Gate
b) Base, Collector, Emitter
c) Anode, Cathode, Grid
d) None
Answer: b
33. NPN transistor has: a) Two P-regions
b) Two N-regions
c) All P-regions
d) One N-region
Answer: b
34. In active mode, the emitter-base junction is: a) Forward biased
b) Reverse biased
c) Open
d) None
Answer: a
35. In CE configuration, input is: a) Base-Collector
b) Collector-Emitter
 c) Base-Emitter
d) Emitter-Base
Answer: c
36. Output of a CE amplifier is: a) In phase with input
b) Out of phase by 90°
c) Out of phase by 180°
d) None
Answer: c
37. Common-emitter configuration offers: a) High input, high output resistance
b) Low gain
c) High voltage gain
d) Negative feedback
Answer: c
38. In a BJT, the base is: a) Thick and lightly doped
b) Thin and lightly doped
c) Thick and heavily doped
d) Thin and heavily doped
Answer: b
39. Collector region is: a) Lightly doped and thin
b) Heavily doped and thin
c) Moderately doped and thick
d) Heavily doped and thick
Answer: c
40. In saturation mode of BJT: a) Both junctions are forward biased
b) Both junctions are reverse biased
c) Base-emitter forward, collector-base reverse
d) No bias
Answer: a
41. The emitter current is: a) Sum of collector and base currents
b) Difference of collector and base
c) Equal to base current
d) Equal to collector current
Answer: a
42. Transistor acts as amplifier in: a) Cutoff region
b) Active region
c) Saturation region
d) Breakdown region
Answer: b
43. Cutoff region means: a) Both junctions reverse biased
b) Emitter-base forward, collector-base reverse
c) Both forward biased
d) None
Answer: a
44. The current gain in CE is: a) α
b) β
c) γ
d) δ
Answer: b
45. If IC = 4.5mA and IB = 0.5mA, what is β? a) 5
b) 8
 c) 9
d) 10
Answer: d
46. A transistor is used as: a) Rectifier
b) Oscillator
c) Switch and amplifier
d) Battery
Answer: c
47. The configuration mostly used in amplification: a) Common base
b) Common emitter
c) Common collector
d) None
Answer: b
48. Collector power dissipation is: a) VCE + IC
b) VCE / IC
c) VCE × IC
d) IC / VCE
Answer: c
49. Alpha (α) is defined as: a) IE / IC
b) IB / IC
c) IC / IE
d) IC / IB
Answer: c
50. In CE configuration, output is taken across: a) Base-Emitter
b) Collector-Emitter
c) Base-Collector
d) None
Answer: b
51. The unit of transistor current gain β is: a) Ampere
b) Volt
c) Ohm
d) Unitless
Answer: d
52. If IE = 10mA and α = 0.9, IC = ? a) 9 mA
b) 0.9 mA
c) 11 mA
d) 1 mA
Answer: a
53. Common base configuration has: a) Low input, high output resistance
b) High input, low output resistance
c) High gain
d) High power
Answer: a
54. Which region controls the operation of transistor? a) Collector
b) Base
c) Emitter
d) All regions
Answer: b
55. A transistor has β = 100. If IB = 50μA, IC = ? a) 0.5 mA
b) 5 mA
 c) 50 mA
d) 0.05 mA
Answer: a
56. In a transistor, majority carriers in base are: a) Holes (p-type base)
b) Electrons (n-type base)
c) None
d) Very few
Answer: d
57. Which of the following has three terminals? a) Diode
b) BJT
c) Resistor
d) Capacitor
Answer: b
58. BJT is a: a) Voltage controlled device
b) Current controlled device
c) Both
d) None
Answer: b
59. Which is not a transistor application? a) Amplifier
b) Oscillator
c) Rectifier
d) Switch
Answer: c
60. When a diode is forward biased: a) High resistance
b) Very high voltage drop
c) Low resistance
d) No current
Answer: c
61. What happens to a diode in reverse bias? a) Conducts heavily
b) Blocks current
c) Acts as resistor
d) Emits light
Answer: b
62. Zener diode is used for: a) Oscillation
b) Rectification
c) Voltage regulation
d) Amplification
Answer: c
63. Breakdown in Zener diode occurs due to: a) High temperature
b) High current
c) High reverse voltage
d) High forward voltage
Answer: c
64. Intrinsic semiconductor is: a) Pure
b) Doped
c) N-type
d) P-type
Answer: a
65. Majority carriers in N-type are: a) Holes
b) Electrons
 c) Ions
d) None
Answer: b
66. P-type semiconductor is formed by doping with: a) Pentavalent atoms
b) Trivalent atoms
c) Tetravalent atoms
d) None
Answer: b
67. Which is not a semiconductor? a) Silicon
b) Germanium
c) Copper
d) Carbon
Answer: c
68. Forward voltage drop across silicon diode is: a) 0.3V
b) 0.7V
c) 1.2V
d) 2.0V
Answer: b
69. A diode allows current in: a) Both directions
b) No direction
c) One direction
d) Depends on polarity
Answer: c
70. In full-wave rectifier, number of diodes used: a) 1
b) 2
c) 3
d) 4
Answer: b
71. In bridge rectifier: a) One diode conducts
b) Two diodes conduct
c) Three conduct
d) Four conduct at a time
Answer: b
72. Main purpose of filter in rectifier: a) Amplify signal
b) Convert AC to DC
c) Remove ripples
d) Increase voltage
Answer: c
73. BJT has: a) Two junctions
b) One junction
c) Three junctions
d) No junctions
Answer: a
74. Which transistor terminal is common in CE configuration? a) Emitter
b) Base
c) Collector
d) All
Answer: a
75. Rectifier converts: a) DC to AC
b) AC to DC
 c) High voltage to low
d) Low voltage to high
Answer: b
76. In an NPN transistor, direction of electron flow: a) Base to emitter
b) Collector to emitter
c) Emitter to base
d) None
Answer: c
77. In PNP transistor, majority carriers are: a) Electrons
b) Holes
c) Ions
d) None
Answer: b
78. NPN transistor symbol shows: a) Arrow on collector
b) Arrow on emitter outwards
c) Arrow inwards
d) No arrow
Answer: b
79. In saturation mode: a) Transistor conducts
b) Transistor switches off
c) Base is reverse biased
d) No current flows
Answer: a
80. Amplification occurs in: a) Saturation region
b) Cutoff region
c) Active region
d) Reverse region
Answer: c
81. Transistor as a switch operates in: a) Active region
b) Reverse region
c) Cutoff and saturation
d) Breakdown
Answer: c
82. Which region is always heavily doped in BJT? a) Collector
b) Base
c) Emitter
d) All equal
Answer: c
83. Reverse saturation current depends on: a) Voltage
b) Temperature
c) Frequency
d) Power
Answer: b
84. When emitter junction is forward biased: a) No current flows
b) High resistance
c) Emitter injects carriers
d) Base absorbs all
Answer: c
85. Purpose of base in BJT: a) Supply carriers
b) Absorb carriers
 c) Control current
d) Store charge
Answer: c
86. A transistor can: a) Act as insulator
b) Be used as rectifier
c) Amplify weak signal
d) Replace a diode
Answer: c
87. Typical base current is: a) Equal to collector
b) Much less than emitter
c) More than emitter
d) Same as emitter
Answer: b
88. Voltage gain of transistor is: a) AV = RC/RE
b) AV = Vout/Vin
c) AV = β
d) None
Answer: b
89. Early effect in transistor refers to: a) Base width modulation
b) Carrier diffusion
c) Thermal breakdown
d) Gain increase
Answer: a
90. Power gain is: a) Voltage gain × current gain
b) Only voltage gain
c) Only current gain
d) Beta squared
Answer: a
91. A switch transistor works in: a) Linear mode
b) Amplification mode
c) Cutoff and saturation
d) Avalanche mode
Answer: c
92. In CE amplifier, phase shift is: a) 90°
b) 0°
c) 180°
d) 270°
Answer: c
93. A transistor’s input resistance in CE mode is: a) High
b) Low
c) Infinite
d) Zero
Answer: b
94. Diode conducts in: a) Reverse bias
b) Forward bias
c) No bias
d) Depends on doping
Answer: b
95. A transistor requires: a) Two DC sources
b) AC supply
 c) One DC source
d) No supply
Answer: c
96. Power supply ripple is reduced using: a) Transformer
b) Rectifier
c) Filter
d) Regulator
Answer: c
97. Transistor collector current mainly depends on: a) Base current
b) Supply voltage
c) Collector resistance
d) Load
Answer: a
98. In an amplifier, the output signal: a) Is weaker than input
b) Has more power
c) Has lower frequency
d) None
Answer: b
99. Load line is used to analyze: a) Diode
b) Transistor operation
c) Resistor behavior
d) Inductance
Answer: b
100. Maximum efficiency of full-wave rectifier: a) 50%
b) 60.6%
c) 81.2%
d) 100%
Answer: c
101. Which rule is used to find current in parallel branches?
a) Ohm’s Law
b) Kirchhoff’s Voltage Law
c) Current Division Rule
d) Voltage Division Rule
Answer: c
102. The resistance of an ideal voltmeter is:
a) Very low
b) Infinite
c) Zero
d) Very high
Answer: b
103. The resistance of an ideal ammeter is:
a) Very high
b) Infinite
c) Zero
d) Moderate
Answer: c
104. Which of these is a unipolar device?
a) BJT
b) Diode
c) MOSFET
 d) None
Answer: c
105. A forward-biased diode has:
a) High resistance
b) Low resistance
c) Infinite resistance
d) Zero resistance
Answer: b
106. Depletion region in PN junction acts as:
a) Conductor
b) Insulator
c) Capacitor
d) Resistor
Answer: b
107. PN junction acts as a switch when:
a) Reverse biased
b) No bias
c) Forward biased
d) Overheated
Answer: c
108. In rectifier, the output DC level is higher in:
a) Half-wave
b) Full-wave
c) Bridge
d) Inverter
Answer: b
109. Transistor CE configuration offers:
a) Low current gain
b) High input resistance
c) High voltage gain
d) Unity gain
Answer: c
110. In active mode, BJT acts as:
a) Diode
b) Switch
c) Amplifier
d) Capacitor
Answer: c
111. Transistor CE mode has how many terminals?
a) 2
b) 3
c) 4
d) 1
Answer: b
112. Semiconductor with 4 valence electrons:
a) Trivalent
b) Pentavalent
c) Tetravalent
d) Monovalent
Answer: c
113. Silicon is widely used because:
a) Expensive
b) Abundant
c) Difficult to dope
d) Unstable
Answer: b
114. Emitter of BJT is:
a) Moderately doped
b) Lightly doped
c) Heavily doped
d) Undoped
Answer: c
115. The leakage current in reverse biased diode is due to:
a) Majority carriers
b) Electrons only
c) Minority carriers
d) Holes only
Answer: c
116. The transistor behaves as a variable:
a) Inductor
b) Capacitor
c) Resistor
d) Diode
Answer: c
117. PN junction in forward bias causes:
a) Barrier width increases
b) Barrier disappears
c) Barrier width decreases
d) Barrier resistance increases
Answer: c
118. Avalanche breakdown occurs due to:
a) High forward voltage
b) High reverse current
c) High reverse voltage
d) High resistance
Answer: c
119. Alpha (α) of a BJT is ratio of:
a) IC/IE
b) IB/IE
c) IE/IC
d) IC/IB
Answer: a
120. Beta (β) of a transistor is:
a) IC/IE
b) IB/IC
c) IC/IB
d) IB/IE
Answer: c
 UNIT 2:-

1. What type of signal has only two states: HIGH and LOW?
a) Analog
b) Digital
c) AC
d) PWM
Answer: b
2. An analog signal is:
a) Continuous
b) Discrete
c) Only HIGH or LOW
d) Irregular
Answer: a
3. Which Arduino pin type is used for reading analog signals?
a) GND
b) A0–A5
c) D0–D13
d) VIN
Answer: b
4. What is the function of the GND pin on Arduino?
a) Analog input
b) Digital output
c) Ground reference
d) Power supply
Answer: c
5. Which Arduino board is most commonly used by beginners?
a) Arduino Due
b) Arduino Mega
c) Arduino Uno
d) Arduino Nano
Answer: c
6. Which pin on Arduino Uno provides 5V output?
a) GND
b) AREF
c) 3.3V
d) 5V
Answer: d
7. What is the purpose of PWM in Arduino?
a) Analog input
b) Digital communication
c) Simulate analog output
d) Power control
Answer: c
8. Which sensor detects obstacles using infrared light?
a) LDR
b) DHT11
c) IR sensor
d) Ultrasonic
Answer: c
9. An LDR changes its resistance based on:
a) Temperature
b) Humidity
c) Light intensity
d) Voltage
Answer: c
10. What is the basic principle of an ultrasonic sensor?
a) Light reflection
b) Magnetic field
c) Sound wave reflection
d) Temperature sensing
Answer: c
11. The speed of sound in air used in ultrasonic sensor calculations is approximately:
a) 330 m/s
b) 1000 m/s
c) 500 m/s
d) 120 m/s
Answer: a
12. DHT11 is used to measure:
a) Sound and temperature
b) Humidity and temperature
c) Motion and temperature
d) Light and humidity
Answer: b
13. What type of signal is output by a DHT11 sensor?
a) Analog
b) PWM
c) Digital
d) AC
Answer: c
14. Which pin on the Arduino Uno is used to reset the board?
a) AREF
b) RST
c) VIN
d) TX
Answer: b
15. What does the AREF pin do?
a) Outputs 5V
b) Analog signal input
c) Reference voltage for analog input
d) Reset function
Answer: c
16. What type of signal has only two states: HIGH and LOW?
a) Analog
b) Digital
c) AC
d) PWM
Answer: b
17. An analog signal is:
a) Continuous
 b) Discrete
c) Only HIGH or LOW
d) Irregular
Answer: a
18. Which Arduino pin type is used for reading analog signals?
a) GND
b) A0–A5
c) D0–D13
d) VIN
Answer: b
19. What is the function of the GND pin on Arduino?
a) Analog input
b) Digital output
c) Ground reference
d) Power supply
Answer: c
20. Which Arduino board is most commonly used by beginners?
a) Arduino Due
b) Arduino Mega
c) Arduino Uno
d) Arduino Nano
Answer: c
21. Which pin on Arduino Uno provides 5V output?
a) GND
b) AREF
c) 3.3V
d) 5V
Answer: d
22. What is the purpose of PWM in Arduino?
a) Analog input
b) Digital communication
c) Simulate analog output
d) Power control
Answer: c
23. Which sensor detects obstacles using infrared light?
a) LDR
b) DHT11
c) IR sensor
d) Ultrasonic
Answer: c
24. An LDR changes its resistance based on:
a) Temperature
b) Humidity
c) Light intensity
d) Voltage
Answer: c
25. What is the basic principle of an ultrasonic sensor?
a) Light reflection
b) Magnetic field
c) Sound wave reflection
 d) Temperature sensing
Answer: c
26. The speed of sound in air used in ultrasonic sensor calculations is approximately:
a) 330 m/s
b) 1000 m/s
c) 500 m/s
d) 120 m/s
Answer: a
27. DHT11 is used to measure:
a) Sound and temperature
b) Humidity and temperature
c) Motion and temperature
d) Light and humidity
Answer: b
28. What type of signal is output by a DHT11 sensor?
a) Analog
b) PWM
c) Digital
d) AC
Answer: c
29. Which pin on the Arduino Uno is used to reset the board?
a) AREF
b) RST
c) VIN
d) TX
Answer: b
30. What does the AREF pin do?
a) Outputs 5V
b) Analog signal input
c) Reference voltage for analog input
d) Reset function
Answer: c
31. Which of the following is a digital sensor?
a) LDR
b) DHT11
c) Thermistor
d) Potentiometer
Answer: b
32. The ultrasonic sensor has how many pins in basic modules?
a) 2
b) 3
c) 4
d) 5
Answer: c
33. What does the "Trig" pin do in ultrasonic sensors?
a) Receives signal
b) Sends trigger pulse
c) Outputs analog data
d) Measures voltage
Answer: b
 34. What does the "Echo" pin in an ultrasonic sensor detect?
a) Light
b) Voltage
c) Reflected sound
d) Temperature
Answer: c
35. What value does an LDR have under high light?
a) High resistance
b) Low resistance
c) No change
d) Infinite resistance
Answer: b

Analog and Digital Signals

1. Which of the following is an analog sensor?

a) IR sensor
b) LDR
c) DHT11
d) Ultrasonic sensor
Answer: b) LDR
Explanation: An LDR (Light Dependent Resistor) produces a continuous range of voltage
values based on light intensity, making it an analog sensor.
2. Digital sensors provide output in:
a) Continuous range
b) Discrete levels
c) Both a and b
d) None of the above
Answer: b) Discrete levels
Explanation: Digital sensors output discrete values, typically representing binary states like
HIGH or LOW.
3. The ADC (Analog to Digital Converter) in Arduino UNO has a resolution of:
a) 8-bit
b) 10-bit
c) 12-bit
d) 16-bit
Answer: b) 10-bit
Explanation: The Arduino UNO's ADC converts analog signals into a 10-bit digital value,
ranging from 0 to 1023. GTU MCQ

Arduino Board (Pin Configuration and Description)

4. The digital pins on Arduino UNO are numbered:

a) 0 to 13
b) 0 to 15
c) 1 to 14
 d) 2 to 13
Answer: a) 0 to 13
Explanation: Arduino UNO has 14 digital I/O pins numbered from 0 to 13.
5. Which pin on Arduino UNO is used for analog reference voltage?
a) AREF
b) VCC
c) GND
d) IOREF
Answer: a) AREF
Explanation: AREF is used to set an external reference voltage for the analog inputs.
Quizizz+5GitHub+5Sanfoundry+5
6. The function of the IOREF pin on Arduino UNO is to:
a) Provide 12V supply
b) Provide reference voltage for analog inputs
c) Provide voltage corresponding to the board's operating voltage
d) Ground the board
Answer: c) Provide voltage corresponding to the board's operating voltage
Explanation: IOREF allows shields to adapt to the voltage level of the board. Sanfoundry

IR Sensor

7. The primary use of an IR sensor is:

a) Measuring temperature
b) Detecting objects
c) Measuring humidity
d) Measuring light intensity
Answer: b) Detecting objects
Explanation: IR sensors are commonly used for object detection by emitting and receiving
infrared light. Sanfoundry
8. An IR sensor typically has how many pins?
a) 2
b) 3
c) 4
d) 5
Answer: b) 3
Explanation: The three pins are VCC, GND, and Signal. Sanfoundry+1Sanfoundry+1
9. When interfacing an IR sensor with Arduino for object detection, the Arduino pin should
be set to:
a) Analog input
b) Digital input
c) PWM output
d) Analog output
Answer: b) Digital input
Explanation: IR sensors output digital signals indicating the presence or absence of an
object.

LDR (Light Dependent Resistor)

 10. An LDR changes its resistance based on:
a) Temperature
b) Light intensity
c) Humidity
d) Sound
Answer: b) Light intensity
Explanation: LDRs decrease resistance with increasing light intensity.
11. LDRs are typically connected to which type of Arduino pin?
a) Digital
b) Analog
c) PWM
d) Serial
Answer: b) Analog
Explanation: Since LDRs provide a range of voltage values, they are connected to analog
pins.

Ultrasonic Sensor (Basic Principle)

12. Ultrasonic sensors measure distance by using:

a) Infrared light
b) Sound waves
c) Radio waves
d) Light waves
Answer: b) Sound waves
Explanation: They emit ultrasonic sound waves and measure the time taken for the echo to
return.
13. The commonly used ultrasonic sensor with Arduino is:
a) HC-SR04
b) DHT11
c) LDR
d) IRF540
Answer: a) HC-SR04
Explanation: HC-SR04 is a popular ultrasonic sensor module for distance measurement.
14. The HC-SR04 sensor has how many pins?
a) 2
b) 3
c) 4
d) 5
Answer: c) 4
Explanation: The pins are VCC, Trig, Echo, and GND.

Temperature Sensor (DHT11/DHT22)

15. DHT11 and DHT22 sensors measure:

a) Temperature only
b) Humidity only
c) Both temperature and humidity
 d) Pressure
Answer: c) Both temperature and humidity
Explanation: These sensors provide digital output for both temperature and humidity
readings.
16. Which of the following is more accurate?
a) DHT11
b) DHT22
c) Both have same accuracy
d) None of the above
Answer: b) DHT22
Explanation: DHT22 offers higher accuracy and a wider range compared to DHT11.

Temperature Sensor (DHT11/DHT22) - continued

17. DHT11 sensor provides output in:

a) Analog voltage
b) Digital signal
c) PWM signal
d) Serial signal
Answer: b) Digital signal
Explanation: DHT11 communicates via a digital signal, not an analog voltage.
18. Which of the following is a correct temperature range for the DHT11 sensor?
a) -40°C to 80°C
b) 0°C to 50°C
c) -20°C to 60°C
d) -10°C to 40°C
Answer: b) 0°C to 50°C
Explanation: DHT11 works between 0°C to 50°C for temperature.
19. Which sensor is better suited for high-precision temperature sensing?
a) DHT11
b) DHT22
c) LDR
d) IR sensor
Answer: b) DHT22
Explanation: DHT22 has higher resolution and accuracy.
20. DHT11 and DHT22 typically have how many pins?
a) 2
b) 3
c) 4
d) 5
Answer: b) 3
Explanation: The common pins are VCC, GND, and Data.

General Arduino Concepts

21. Arduino UNO uses which microcontroller?

a) ATmega16
 b) ATmega32
c) ATmega328P
d) PIC16F877A
Answer: c) ATmega328P
Explanation: Arduino UNO is built around the ATmega328P microcontroller.
22. Which Arduino function sets the mode of a pin?
a) pinType()
b) digitalWrite()
c) pinMode()
d) setupPin()
Answer: c) pinMode()
Explanation: pinMode(pin, mode) configures a pin as input or output.
23. What is the maximum voltage tolerated by the analog pins of Arduino UNO?
a) 12V
b) 9V
c) 5V
d) 3.3V
Answer: c) 5V
Explanation: Applying more than 5V may damage the analog input.
24. Which Arduino function reads the value from a digital input pin?
a) digitalRead()
b) analogRead()
c) readPin()
d) getInput()
Answer: a) digitalRead()
Explanation: digitalRead(pin) returns HIGH or LOW for digital input.
25. The function analogRead(A0) returns a value between:
a) 0 and 5
b) 0 and 1023
c) 0 and 255
d) 0 and 4095
Answer: b) 0 and 1023
Explanation: 10-bit ADC returns values from 0 to 1023.
26. PWM pins on Arduino UNO are marked with:
a) Square symbol
b) Dot symbol
c) Tilde ()
d) Arrow symbol
Answer: c) Tilde ()
Explanation: Pins like 3, 5, 6, 9, 10, 11 are PWM-enabled and marked with ~.
27. Which function is used to generate PWM signals in Arduino?
a) analogWrite()
b) digitalWrite()
c) analogRead()
d) pwmWrite()
Answer: a) analogWrite()
Explanation: analogWrite(pin, value) generates a PWM signal.
28. How many analog input pins are there in Arduino UNO?
a) 4
b) 5
c) 6
 d) 8
Answer: c) 6
Explanation: Arduino UNO has 6 analog input pins labeled A0 to A5.
29. What is the default baud rate of Arduino Serial Monitor?
a) 4800
b) 9600
c) 14400
d) 57600
Answer: b) 9600
Explanation: Common default baud rate used for serial communication.
30. To begin serial communication, which function is used in Arduino?
a) Serial.begin()
b) serialStart()
c) digitalStart()
d) beginSerial()
Answer: a) Serial.begin()
Explanation: Starts the serial communication at specified baud rate.

Arduino – Input/Output and Programming

31. Which function is used to turn an LED ON at pin 13 in Arduino?

a) pinMode(13, LOW);
b) digitalRead(13);
c) digitalWrite(13, HIGH);
d) analogWrite(13, LOW);
Answer: c) digitalWrite(13, HIGH);
Explanation: digitalWrite() sets a digital pin to HIGH or LOW.
32. What does delay(1000); do in Arduino code?
a) Delays by 1 second
b) Delays by 100 seconds
c) Delays by 1 millisecond
d) Delays by 10 seconds
Answer: a) Delays by 1 second
Explanation: The delay() function uses milliseconds. 1000 ms = 1 s.
33. The loop() function in Arduino:
a) Runs once
b) Runs forever
c) Runs twice
d) Never runs
Answer: b) Runs forever
Explanation: loop() executes repeatedly after setup().
34. To read the value from an analog sensor on A1, we use:
a) analogRead(A1)
b) analogWrite(A1)
c) digitalRead(A1)
d) digitalWrite(A1)
Answer: a) analogRead(A1)
Explanation: Reads analog voltage from pin A1.
 35. Which of the following is NOT a valid Arduino data type?
a) int
b) float
c) char
d) digit
Answer: d) digit
Explanation: digit is not a recognized Arduino data type.
36. Which Arduino IDE file extension is used for sketches?
a) .ino
b) .ard
c) .ardx
d) .cpp
Answer: a) .ino
Explanation: Arduino programs are saved with .ino extension.
37. To power Arduino UNO externally, which pin is used?
a) GND
b) AREF
c) VIN
d) IOREF
Answer: c) VIN
Explanation: VIN pin allows you to power the Arduino using an external supply.
38. Which Arduino function initializes the pin mode?
a) initPin()
b) setPin()
c) pinMode()
d) modePin()
Answer: c) pinMode()
Explanation: pinMode(pin, INPUT/OUTPUT) sets pin mode.
39. Which pin is used for built-in LED on Arduino UNO?
a) 10
b) 12
c) 13
d) 9
Answer: c) 13
Explanation: Pin 13 is connected to the onboard LED.
40. What does PWM stand for?
a) Pulse Wave Method
b) Period Width Measure
c) Pulse Width Modulation
d) Power Width Method
Answer: c) Pulse Width Modulation
Explanation: PWM is a technique for simulating analog output.

Sensors – Continued

41. Which parameter does LDR directly affect in a circuit?

a) Voltage drop
b) Resistance
c) Current source
 d) Capacitance
Answer: b) Resistance
Explanation: LDR’s resistance varies with light intensity.
42. Which signal type does an ultrasonic sensor produce to calculate distance?
a) Infrared
b) Laser
c) Radio
d) Sound wave
Answer: d) Sound wave
Explanation: Ultrasonic sensors use high-frequency sound pulses.
43. The Echo pin of the ultrasonic sensor is used to:
a) Send sound pulses
b) Detect objects
c) Measure distance
d) Receive reflected sound
Answer: d) Receive reflected sound
Explanation: The Echo pin detects the returning sound pulse.
44. Which type of signal does the DHT11 output?
a) Analog
b) PWM
c) Serial digital
d) I2C
Answer: c) Serial digital
Explanation: DHT11 sends digital data in a serial bitstream.
45. Which of the following sensors is commonly used in automatic streetlights?
a) IR sensor
b) Ultrasonic sensor
c) LDR
d) DHT11
Answer: c) LDR
Explanation: LDRs detect light level and switch lights ON/OFF.
46. DHT22 can measure humidity from:
a) 20% to 80%
b) 0% to 100%
c) 10% to 90%
d) 30% to 70%
Answer: b) 0% to 100%
Explanation: DHT22 has a full-range humidity sensing capability.
47. Which sensor is least affected by ambient light?
a) LDR
b) IR sensor
c) Ultrasonic sensor
d) Photodiode
Answer: c) Ultrasonic sensor
Explanation: Ultrasonic sensors use sound, not light, making them suitable for all lighting
conditions.
48. What is the typical range of an HC-SR04 ultrasonic sensor?
a) 2 cm to 80 cm
b) 5 cm to 200 cm
c) 2 cm to 400 cm
d) 1 cm to 50 cm
 Answer: c) 2 cm to 400 cm
Explanation: It can detect objects within 2 to 400 cm range.
49. In Arduino, which command prints text to the Serial Monitor?
a) write()
b) println()
c) printText()
d) Serial.print()
Answer: d) Serial.print()
Explanation: Use Serial.print() or Serial.println() to output text to the monitor.
50. Which of the following is required to interface a sensor with Arduino?
a) Correct power supply
b) Proper pin connection
c) Matching signal type (analog/digital)
d) All of the above
Answer: d) All of the above
Explanation: All these factors ensure proper sensor interfacing

51. Which signal is continuous and can take any value within a range?
a) Analog
b) Digital
c) PWM
d) Boolean
Answer: a) Analog
Explanation: Analog signals are continuous in nature.
52. Which signal type has only two levels: HIGH or LOW?
a) Analog
b) Digital
c) Serial
d) Modulated
Answer: b) Digital
Explanation: Digital signals are binary (0 or 1, LOW or HIGH).
53. What is the voltage level for digital HIGH in Arduino UNO?
a) 0V
b) 2.5V
c) 3.3V
d) 5V
Answer: d) 5V
Explanation: Arduino UNO operates at 5V logic level.
54. What is the voltage level for digital LOW in Arduino UNO?
a) 0V
b) 1.5V
c) 3.3V
d) 5V
Answer: a) 0V
Explanation: Digital LOW is considered 0V.
55. What does the analog-to-digital converter (ADC) in Arduino do?
a) Converts voltage to current
b) Converts analog signals to digital values
c) Converts digital to analog signals
d) Converts PWM to serial
 Answer: b) Converts analog signals to digital values
Explanation: ADC converts varying analog voltages to a digital number.
56. Which Arduino function sends a binary signal (ON/OFF)?
a) digitalRead()
b) digitalWrite()
c) analogRead()
d) analogWrite()
Answer: b) digitalWrite()
Explanation: digitalWrite() sets a pin to HIGH or LOW.
57. Which sensor is most suitable for obstacle detection in autonomous robots?
a) DHT11
b) IR sensor
c) LDR
d) Temperature sensor
Answer: b) IR sensor
Explanation: IR sensors detect objects by emitting and receiving infrared light.
58. Which sensor is sensitive to light intensity?
a) IR sensor
b) Ultrasonic sensor
c) LDR
d) DHT22
Answer: c) LDR
Explanation: LDR (Light Dependent Resistor) varies resistance with light.
59. Which sensor uses temperature-sensitive resistors to measure temperature?
a) LDR
b) Ultrasonic sensor
c) Thermistor
d) IR sensor
Answer: c) Thermistor
Explanation: Thermistors are commonly used for temperature sensing.
60. Which of the following sensors use a trigger and echo mechanism?
a) IR sensor
b) DHT11
c) LDR
d) Ultrasonic sensor
Answer: d) Ultrasonic sensor
Explanation: HC-SR04 uses Trigger to send and Echo to receive sound waves.

Arduino IDE and Code Logic

61. In Arduino, what is the role of the setup() function?

a) Loops the code
b) Ends the program
c) Initializes variables and pin modes
d) Stores sensor values
Answer: c) Initializes variables and pin modes
Explanation: setup() runs once at the start of the sketch.
62. How many PWM-capable pins are available on Arduino UNO?
a) 4
b) 5
c) 6
d) 8
Answer: c) 6
Explanation: PWM is available on pins 3, 5, 6, 9, 10, and 11.
63. Which Arduino pin provides 3.3V output?
a) AREF
b) VIN
c) 3.3V
d) IOREF
Answer: c) 3.3V
Explanation: 3.3V pin provides regulated 3.3V power.
64. Which function is used to print data with a newline in Serial Monitor?
a) Serial.display()
b) Serial.write()
c) Serial.print()
d) Serial.println()
Answer: d) Serial.println()
Explanation: println() appends a newline after printing the data.
65. Which statement correctly sets pin 2 as an input?
a) input(pin2);
b) pinSetup(2, INPUT);
c) pinMode(2, INPUT);
d) digitalRead(2, ON);
Answer: c) pinMode(2, INPUT);
Explanation: Use pinMode() to define pin direction.
66. To delay a program by half a second, which is correct?
a) delay(0.5);
b) wait(500);
c) delay(500);
d) pause(0.5);
Answer: c) delay(500);
Explanation: delay() accepts time in milliseconds.
67. Which of these sensors does NOT provide distance measurement?
a) Ultrasonic sensor
b) IR sensor
c) DHT11
d) Radar sensor
Answer: c) DHT11
Explanation: DHT11 measures temperature and humidity, not distance.
68. Which function will produce a PWM signal on pin 6?
a) analogRead(6)
b) analogWrite(6, 255)
c) pwmWrite(6, 100)
d) digitalWrite(6, HIGH)
Answer: b) analogWrite(6, 255)
Explanation: analogWrite() creates a PWM output.
69. Which component is required to measure temperature using DHT11?
a) Analog comparator
b) Digital input pin
c) PWM pin
d) ADC pin
Answer: b) Digital input pin
Explanation: DHT11 sends data via a digital line.
70. Which Arduino board is best for beginner-level sensor projects?
a) Arduino Due
b) Arduino Mega
c) Arduino Leonardo
d) Arduino UNO
Answer: d) Arduino UNO
Explanation: Arduino UNO is simple, versatile, and beginner-friendly

71. Which sensor is preferred for motion detection in security systems?

a) DHT22
b) PIR sensor
c) LDR
d) IR sensor
Answer: b) PIR sensor
Explanation: Passive Infrared (PIR) sensors detect motion based on body heat.
72. Which pin should be used in Arduino to read analog data from a sensor?
a) D0–D13
b) A0–A5
c) PWM pins
d) RESET
Answer: b) A0–A5
Explanation: Analog sensors should be connected to analog input pins.
73. Which sensor gives better humidity accuracy?
a) DHT11
b) LDR
c) DHT22
d) Ultrasonic
Answer: c) DHT22
Explanation: DHT22 offers more precise temperature and humidity readings than
DHT11.
74. What does the term "threshold value" mean in an LDR circuit?
a) Max resistance
b) Light level where circuit action changes
c) Temperature limit
d) Voltage drop limit
Answer: b) Light level where circuit action changes
Explanation: Threshold is the point where output behavior switches.
75. Which component is used to control current in a sensor circuit?
a) Resistor
b) Capacitor
c) Diode
d) Inductor
 Answer: a) Resistor
Explanation: Resistors manage current flow.
76. What value will analogRead(A0) return in complete darkness with an LDR?
a) 0
b) 1023
c) Random
d) 512
Answer: a) 0
Explanation: No light = high resistance = near 0 analog value.
77. If you reverse the polarity of the ultrasonic sensor connections, it will:
a) Still work
b) Overheat
c) Show reverse values
d) Not work or may be damaged
Answer: d) Not work or may be damaged
Explanation: Always follow correct VCC and GND connection.
78. Which component stores electrical charge in sensor circuits?
a) Resistor
b) Diode
c) Capacitor
d) Transistor
Answer: c) Capacitor
Explanation: Capacitors store and release charge.
79. Which of the following can measure environmental temperature?
a) IR sensor
b) DHT22
c) Ultrasonic sensor
d) PIR sensor
Answer: b) DHT22
Explanation: DHT22 provides digital temp & humidity readings.
80. Which sensor needs a 1-second delay between readings?
a) DHT11
b) Ultrasonic
c) IR sensor
d) LDR
Answer: a) DHT11
Explanation: DHT11 needs at least 1 second between readings.

General Concepts – Signal, Boards, and Coding

81. What does HIGH mean in Arduino logic?

a) 0V
b) 3.3V
c) 5V
d) Floating
Answer: c) 5V
Explanation: HIGH means logic 1 or +5V in Arduino UNO.
82. Which function reads digital values in Arduino?
a) analogRead()
b) digitalRead()
c) readDigital()
d) read()
Answer: b) digitalRead()
83. What happens if you do not declare pinMode in setup()?
a) Program crashes
b) Pin behaves randomly
c) Defaults to input
d) It works anyway
Answer: c) Defaults to input
84. Which pin would you use for sending serial data from Arduino to a PC?
a) RX
b) TX
c) SDA
d) SCL
Answer: b) TX
Explanation: TX = Transmit, used for sending serial data.
85. Which function initiates serial communication in Arduino?
a) Serial.begin()
b) startSerial()
c) Serial.connect()
d) connectSerial()
Answer: a) Serial.begin()
86. What is the default baud rate for Serial communication in Arduino?
a) 4800
b) 19200
c) 9600
d) 115200
Answer: c) 9600
87. What is the role of GND pin in Arduino board?
a) Acts as input
b) Powers the board
c) Reference point for voltage
d) Sends digital signal
Answer: c) Reference point for voltage
88. In Arduino, analogWrite() generates what type of signal?
a) Pure analog
b) Pulse Width Modulation (PWM)
c) Digital LOW
d) Serial
Answer: b) PWM
89. Which of the following is not a digital sensor?
a) IR sensor
b) Ultrasonic sensor
c) LDR
d) DHT11
Answer: c) LDR
Explanation: LDR gives an analog output.
 90. What does Serial.available() check?
a) If USB is connected
b) If data is ready to be sent
c) If data is available to read
d) Number of connected devices
Answer: c) If data is available to read

Final 10 Questions – Miscellaneous Applications

91. How many digital I/O pins does Arduino UNO have?
a) 10
b) 12
c) 14
d) 16
Answer: c) 14
92. To blink an LED ON and OFF continuously, which two functions are essential?
a) delay() and tone()
b) digitalWrite() and delay()
c) loop() and setup()
d) print() and read()
Answer: b) digitalWrite() and delay()
93. A buzzer connected to Arduino can be activated using:
a) digitalRead()
b) analogWrite()
c) digitalWrite()
d) Serial.begin()
Answer: c) digitalWrite()
94. Which board is suitable for compact wearable Arduino projects?
a) UNO
b) Mega
c) Nano
d) Lilypad
Answer: d) Lilypad
95. Which sensor is used in obstacle-avoiding robots?
a) Temperature sensor
b) LDR
c) Ultrasonic sensor
d) DHT11
Answer: c) Ultrasonic sensor
96. In Arduino, HIGH corresponds to binary:
a) 0
b) 1
c) 10
d) 11
Answer: b) 1
97. Which sensor has a longer range: IR or Ultrasonic?
a) IR
 b) Ultrasonic
Answer: b) Ultrasonic
98. Which component can protect Arduino from overcurrent?
a) Fuse
b) Resistor
c) Capacitor
d) Potentiometer
Answer: a) Fuse
99. Which Arduino function converts sensor value to voltage manually?
a) map()
b) analogRead()
c) digitalWrite()
d) convert()
Answer: a) map()
100. What is the role of the AREF pin in Arduino?
a) Resets the board
b) External analog reference voltage
c) Connects analog pins
d) Measures current
Answer: b) External analog reference voltage

121. What will this IR sensor code print when it detects an obstacle?
cpp
CopyEdit
int irSensor = 2;
void setup() {
pinMode(irSensor, INPUT);
Serial.begin(9600);
}
void loop() {
int val = digitalRead(irSensor);
Serial.println(val);
}

a) 0
b) 1
c) Depends on object
d) Both a and c

Answer: d) Both a and c

Explanation: IR sensor returns 0 (LOW) when an object is detected and 1 (HIGH) when not
detected (varies by module).

122. Which function is used to read temperature from DHT11?

a) readTemp()
b) getTemp()
c) readTemperature()
d) analogRead()

Answer: c) readTemperature()

123. In this DHT11 setup, which part is incorrect?

cpp
CopyEdit
#include <DHT.h>
DHT dht(7, DHT11);
void loop() {
float t = dht.readTemperature();
Serial.println(t);
}

a) DHT11 initialization
b) No setup()
c) Wrong library
d) Nothing wrong

Answer: b) No setup()
Explanation: dht.begin(); must be called inside setup().

124. Identify what this code does:

cpp
CopyEdit
int echo = 3;
int trig = 2;
long duration;
void loop() {
digitalWrite(trig, LOW);
delayMicroseconds(2);
digitalWrite(trig, HIGH);
delayMicroseconds(10);
digitalWrite(trig, LOW);
duration = pulseIn(echo, HIGH);
}

a) Sends IR signal
b) Turns on LED
c) Measures time taken for echo return
d) Reads light intensity

Answer: c) Measures time taken for echo return

125. What is the output of pulseIn(echoPin, HIGH)?

a) Distance in cm
b) Time in milliseconds
c) Time in microseconds
d) Voltage

Answer: c) Time in microseconds

126. Which pin does LDR usually connect to?

a) Digital
b) PWM
c) Analog (A0–A5)
d) GND

Answer: c) Analog (A0–A5)

127. Find the issue in the LDR code:

cpp
CopyEdit
int ldr = A1;
void setup() {
pinMode(ldr, INPUT);
}
void loop() {
int value = digitalRead(ldr);
}

a) analogRead should be used

b) digitalRead is correct
c) No issue
d) Setup is incorrect

Answer: a) analogRead should be used

Explanation: LDR gives analog output → use analogRead().

128. What value range does LDR return using analogRead?

a) 0–1
b) 0–1023
c) 0–255
d) 1–10

Answer: b) 0–1023

129. What is the correct delay for triggering ultrasonic sensor?

cpp
CopyEdit
digitalWrite(trig, HIGH);
delayMicroseconds(?);
digitalWrite(trig, LOW);

a) 2 µs
b) 10 µs
c) 100 µs
d) 1 ms

Answer: b) 10 µs

130. How is distance calculated in ultrasonic sensor?

cpp
CopyEdit
distance = duration / ?;

a) 58
b) 2
c) 29
d) 0.5

Answer: a) 58
Explanation: distance (cm) = duration / 58

131. What will this DHT11 code print?

cpp
CopyEdit
float h = dht.readHumidity();
Serial.println(h);

a) Temperature in °C
b) Humidity in %
c) Voltage
d) Nothing

Answer: b) Humidity in %

132. In this code, what is analogWrite(led, 127); doing?

cpp
CopyEdit
int led = 9;
analogWrite(led, 127);

a) Turns LED off

b) Full brightness
c) Half brightness
d) Blinking LED

Answer: c) Half brightness

Explanation: PWM value ranges from 0 to 255

133. What is the output of this IR sensor setup if no object is in front?

cpp
CopyEdit
int ir = 2;
int val = digitalRead(ir);

a) 1
b) 0
c) Depends on lighting
d) Always HIGH

Answer: a) 1

134. What happens when you don’t call dht.begin() in setup()?

a) Sensor still works

b) No output
c) Arduino crashes
d) Wrong temperature

Answer: b) No output
135. What will be the output of this code?
cpp
CopyEdit
float temp = dht.readTemperature();
if (temp > 30) {
digitalWrite(fan, HIGH);
}

a) Fan turns ON if temp > 30°C

b) Fan always ON
c) Fan turns ON at 30°F
d) Nothing happens

Answer: a) Fan turns ON if temp > 30°C

136. Which delay is preferred between DHT11 readings?

a) 100 ms
b) 500 ms
c) 1000 ms
d) 2000 ms

Answer: d) 2000 ms
Explanation: To allow stable reading from DHT11.

137. Choose correct function: Read analog signal from LDR

a) digitalRead(ldr)
b) analogRead(ldr)
c) pinMode(ldr)
d) readSensor()

Answer: b) analogRead(ldr)

138. Ultrasonic Sensor - Which pin is output?

a) Trig
b) Echo
c) GND
d) VCC
 Answer: b) Echo

139. Which code correctly calculates distance in cm using ultrasonic?

cpp
CopyEdit
long duration = pulseIn(echo, HIGH);
int distance = duration / 58;

a) Correct
b) Incorrect
c) Should use /29
d) Use delay instead

Answer: a) Correct

140. Why is delayMicroseconds(2) added before triggering ultrasonic pulse?

a) Warm-up
b) Sensor reset
c) Clean signal
d) Pulse synchronization

Answer: d) Pulse synchronization

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You said:
like which pin what do where use more details mcq about arduino also

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Great! Let's now focus on Arduino board details — pin configuration, functions, pin types (digital,
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detailed MCQs. These will really help solidify your core understanding of the Arduino board itself.
🧩 Detailed Arduino MCQs: Pins, Functions, and Uses (Part 1)

30+ high-quality questions with answers and explanations

141. How many digital I/O pins does Arduino UNO have?

a) 12
b) 14
c) 6
d) 8

Answer: b) 14
Explanation: Digital pins are numbered from 0 to 13.

142. Which Arduino UNO pins support PWM output?

a) 2, 3, 4, 5, 6, 7
b) 3, 5, 6, 9, 10, 11
c) A0–A5
d) 0, 1

Answer: b) 3, 5, 6, 9, 10, 11
Explanation: These have PWM (~) symbol and support analogWrite().

143. What is the function of pin 13 on Arduino UNO?

a) Reset pin
b) Built-in LED control
c) Analog sensor pin
d) I2C pin

Answer: b) Built-in LED control

144. What is the purpose of the AREF pin in Arduino UNO?

a) Ground pin
b) Digital output
c) Reference voltage for analog inputs
d) Reset signal

Answer: c) Reference voltage for analog inputs

145. Which pins are used for I2C communication?

a) 0 and 1
b) 3 and 4
c) A4 and A5
d) 7 and 8

Answer: c) A4 and A5
Explanation: A4 (SDA) and A5 (SCL) on UNO

146. What is the function of pin 0 and 1 on Arduino UNO?

a) SPI communication
b) PWM output
c) Serial communication (RX, TX)
d) Analog input

Answer: c) Serial communication (RX, TX)

147. Which function is used to define a pin’s behavior as input or output?

a) setPin()
b) pinMode()
c) digitalWrite()
d) definePin()

Answer: b) pinMode()

148. Which of the following is a valid analog pin on Arduino UNO?

a) 13
b) 6
c) A1
d) TX
 Answer: c) A1

149. Which pins are connected to the Serial Monitor by default?

a) 3 and 4
b) A4 and A5
c) 0 and 1
d) 5 and 6

Answer: c) 0 and 1
Explanation: Pin 0 = RX, Pin 1 = TX

150. What will this code do?

cpp
CopyEdit
pinMode(9, OUTPUT);
analogWrite(9, 255);

a) Turns off pin 9

b) Sends PWM at 100% duty cycle
c) Sends LOW voltage
d) Reads analog input

Answer: b) Sends PWM at 100% duty cycle

151. Which pin on Arduino UNO resets the board when pulled LOW?

a) GND
b) 13
c) VIN
d) RESET

Answer: d) RESET

152. What is the use of VIN pin on Arduino board?

a) Ground pin
b) Digital output
c) Input voltage when using external power
d) Sends serial data

Answer: c) Input voltage when using external power

153. How many analog input pins are there on the UNO?

a) 4
b) 5
c) 6
d) 8

Answer: c) 6
Explanation: A0 to A5 are available.

154. Which of the following functions sets a digital pin HIGH?

a) digitalWrite(pin, 1)
b) digitalWrite(pin, HIGH)
c) setPin(pin, 1)
d) analogWrite(pin, 255)

Answer: b) digitalWrite(pin, HIGH)

155. What is the voltage level of HIGH on a digital pin in UNO?

a) 0V
b) 3.3V
c) 5V
d) 12V

Answer: c) 5V

156. What happens if you connect an analog sensor to a digital pin?

a) Sensor will work fine

b) Sensor may give wrong reading
c) Board may burn
d) Arduino will auto-detect
 Answer: b) Sensor may give wrong reading
Explanation: Analog sensors need analogRead, which digital pins don’t support.

157. Which of these statements is true about analogWrite()?

a) It outputs true analog signal

b) It uses PWM
c) Only works on A0–A5
d) Only works on pins 0–7

Answer: b) It uses PWM

158. Which pin is used as the default LED output?

a) Pin 0
b) Pin 13
c) A5
d) TX

Answer: b) Pin 13

159. What is the use of GND pin on Arduino?

a) Supplies 5V
b) For analog output
c) Common ground for circuits
d) Serial signal

Answer: c) Common ground for circuits

160. What type of pin is used for reading sensors like DHT11?

a) Analog only
b) Digital only
c) PWM only
d) Both analog and digital

Answer: b) Digital only

Explanation: DHT11 uses a single digital pin for communication.
101. What does the following code do?
cpp
CopyEdit
int sensor = 7;
void setup() {
pinMode(sensor, INPUT);
Serial.begin(9600);
}
void loop() {
int value = digitalRead(sensor);
Serial.println(value);
delay(1000);
}

a) Reads analog data from sensor

b) Reads temperature
c) Reads digital input from pin 7
d) Turns on LED

Answer: c) Reads digital input from pin 7

Explanation: The pin is set as INPUT, and digitalRead reads its HIGH/LOW state.

102. What type of sensor would best suit the above code?

a) LDR
b) IR Sensor
c) DHT11
d) Ultrasonic

Answer: b) IR Sensor
Explanation: IR sensor usually gives HIGH/LOW output, suitable for digitalRead().

103. What is the purpose of the following code?

cpp
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int ldrPin = A0;
void loop() {
int lightValue = analogRead(ldrPin);
Serial.println(lightValue);
delay(1000);
}

a) Turn on an LED
b) Read light intensity
c) Measure humidity
d) Control fan speed
 Answer: b) Read light intensity
Explanation: LDR gives analog voltage which is read by analogRead().

104. Which range does analogRead() return in Arduino UNO?

a) 0 to 1
b) 0 to 1023
c) 0 to 255
d) 0 to 10

Answer: b) 0 to 1023
Explanation: 10-bit ADC converts analog voltage to digital in that range.

105. Identify the output:

cpp
CopyEdit
digitalWrite(13, HIGH);
delay(1000);
digitalWrite(13, LOW);
delay(1000);

a) Blinks LED at pin 13 every 2 seconds

b) Turns LED off
c) No effect
d) Continuous ON state

Answer: a) Blinks LED at pin 13 every 2 seconds

106. What is missing in this code snippet for ultrasonic sensor?

cpp
CopyEdit
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);

a) pinMode declarations
b) Trigger delay
c) Serial.begin
d) None

Answer: a) pinMode declarations

107. In Ultrasonic sensor, what does pulseIn(echoPin, HIGH) do?

a) Triggers signal
b) Measures time of HIGH signal
c) Outputs distance
d) None

Answer: b) Measures time of HIGH signal

108. What is the formula to calculate distance (in cm) from time?

a) time / 29 / 2
b) time * 2 / 10
c) time * 2 / 100
d) time / 58

Answer: d) time / 58

109. What is wrong in the following DHT11 code?

cpp
CopyEdit
#include "DHT.h"
DHT dht(2, DHT11);
void loop() {
float temp = dht.readTemperature();
Serial.println(temp);
}

a) Missing setup() function

b) Incorrect library
c) Missing pinMode
d) No delay between readings

Answer: a) Missing setup() function

Explanation: setup() is needed to initialize the sensor.

110. What is the role of DHT.readHumidity()?

a) Returns temperature
b) Returns analog voltage
c) Returns humidity in %
d) Sends data to cloud

Answer: c) Returns humidity in %

111. Complete this LDR-controlled LED code:

cpp
CopyEdit
int ldrPin = A0;
int led = 13;
void loop() {
int ldrVal = analogRead(ldrPin);
if (ldrVal < 300) {
digitalWrite(led, HIGH);
} else {
digitalWrite(led, LOW);
}
}

What does this code do?

a) Turns on LED in bright light
b) Blinks LED
c) Turns on LED in darkness
d) Controls LED brightness

Answer: c) Turns on LED in darkness

112. Which sensor setup uses both analog and digital pins?

a) IR sensor
b) Ultrasonic
c) LDR
d) None

Answer: b) Ultrasonic
Explanation: Uses digital trigger and echo but logic can involve analog interpretation of
timing.

113. Which part of this code reads IR detection?

cpp
CopyEdit
int irVal = digitalRead(2);
a) analogRead
b) digitalRead
c) Serial.print
d) digitalWrite

Answer: b) digitalRead

114. DHT11 delay recommendation is:

a) No delay needed
b) 2 seconds
c) 10 ms
d) 0.5 sec

Answer: b) 2 seconds
Explanation: DHT11 needs 1–2 seconds between readings.

115. What happens if you call analogRead() on a digital pin?

a) It works
b) Error
c) Always returns 0
d) Crashes board

Answer: b) Error

116. What kind of sensor is DHT22?

a) Digital output
b) Analog
c) Analog + Digital
d) None

Answer: a) Digital output

117. In Arduino, pinMode(pin, OUTPUT) does what?

a) Enables analog read

b) Sets pin to send signals
c) Resets board
d) None
 Answer: b) Sets pin to send signals

118. What is the difference between analogWrite() and digitalWrite()?

a) analogWrite supports floating points

b) digitalWrite only supports HIGH/LOW
c) analogWrite uses 0–1023 range
d) All of the above

Answer: b) digitalWrite only supports HIGH/LOW

119. Which library is needed to work with DHT11/DHT22?

a) IRremote
b) LiquidCrystal
c) DHT.h
d) Servo.h

Answer: c) DHT.h

120. What is the role of delayMicroseconds() in ultrasonic code?

a) Long wait
b) Short pulse
c) Send beep
d) Send trigger wave

Answer: b) Short pulse