Q.1 Which of the following best defines a sensor in IoT systems?
A device that stores data
A device that converts energy into motion
A device that measures physical properties
A device that connects to the internet
Explanation - Sensors are used to detect and measure physical phenomena like temperature, pressure, or light, converting them into electrical signals.
Correct answer is: A device that measures physical properties
Q.2 An actuator in an IoT system primarily performs which function?
Sense environmental changes
Convert signals into physical action
Store sensor data
Transmit wireless signals
Explanation - Actuators respond to control signals by performing physical actions such as moving, rotating, or adjusting devices.
Correct answer is: Convert signals into physical action
Q.3 Which type of sensor is commonly used to measure temperature in IoT devices?
Accelerometer
Thermistor
Gyroscope
Proximity sensor
Explanation - Thermistors are temperature-sensitive resistors used for temperature measurements in IoT systems.
Correct answer is: Thermistor
Q.4 What does an accelerometer measure?
Speed
Position
Acceleration
Light intensity
Explanation - Accelerometers measure changes in velocity, often used in mobile and IoT devices to detect orientation and motion.
Correct answer is: Acceleration
Q.5 Which of the following is an example of an actuator?
Thermocouple
DC motor
Pressure sensor
Photodiode
Explanation - A DC motor is an actuator as it converts electrical energy into mechanical motion.
Correct answer is: DC motor
Q.6 In IoT, sensors generally provide data in which form?
Physical movement
Electrical signals
Text files
Actuator commands
Explanation - Sensors detect environmental parameters and output corresponding electrical signals that can be processed digitally.
Correct answer is: Electrical signals
Q.7 Which sensor is most suitable for detecting motion in smart lighting systems?
Temperature sensor
Proximity sensor
PIR sensor
Barometer
Explanation - PIR (Passive Infrared) sensors detect infrared radiation changes caused by motion, making them ideal for smart lighting.
Correct answer is: PIR sensor
Q.8 An actuator that regulates water flow in a smart irrigation system is called?
Water sensor
Solenoid valve
Humidity sensor
Thermostat
Explanation - A solenoid valve acts as an actuator to control water flow electronically in irrigation systems.
Correct answer is: Solenoid valve
Q.9 Which sensor is typically used in smartphones to adjust screen orientation?
Gyroscope
Proximity sensor
Barometer
Thermistor
Explanation - Gyroscopes measure angular rotation, allowing smartphones to adjust display orientation automatically.
Correct answer is: Gyroscope
Q.10 What type of sensor is a photodiode?
Motion sensor
Light sensor
Pressure sensor
Temperature sensor
Explanation - A photodiode detects light intensity and converts it into electrical current, widely used in IoT applications.
Correct answer is: Light sensor
Q.11 Which of the following is NOT an example of an actuator?
Stepper motor
Relay
Servo motor
Barometer
Explanation - A barometer is a pressure sensor, not an actuator, as it only measures rather than acts.
Correct answer is: Barometer
Q.12 What is the role of a pressure sensor in IoT systems?
To detect light
To measure force per unit area
To convert signals into motion
To store data
Explanation - Pressure sensors detect the amount of force applied per unit area, useful in healthcare and industrial IoT.
Correct answer is: To measure force per unit area
Q.13 Which actuator is commonly used in robotic arms for precision movement?
Servo motor
Thermistor
LDR
Barometer
Explanation - Servo motors provide precise control of angular or linear position, making them suitable for robotic applications.
Correct answer is: Servo motor
Q.14 A humidity sensor is used to measure:
Air temperature
Moisture content in air
Water flow
Soil pressure
Explanation - Humidity sensors detect water vapor content in the atmosphere, important in smart agriculture and weather monitoring.
Correct answer is: Moisture content in air
Q.15 Which sensor would be ideal for detecting gas leaks?
LDR
MQ sensor
Accelerometer
Thermocouple
Explanation - MQ series sensors are widely used for detecting gases like methane, carbon monoxide, or smoke in IoT applications.
Correct answer is: MQ sensor
Q.16 Which of the following is an output device in IoT?
Humidity sensor
Relay
PIR sensor
Thermistor
Explanation - A relay acts as an actuator/output device by switching electrical circuits on or off.
Correct answer is: Relay
Q.17 An LDR (Light Dependent Resistor) is mainly used to detect?
Air pressure
Motion
Light intensity
Sound
Explanation - LDRs change resistance based on light levels, commonly used in streetlights and IoT lighting systems.
Correct answer is: Light intensity
Q.18 Which of the following actuators is used for creating vibrations in smartphones?
DC motor
Piezoelectric actuator
Relay
Solenoid valve
Explanation - Piezoelectric actuators generate vibrations using piezoelectric materials in smartphones and haptic devices.
Correct answer is: Piezoelectric actuator
Q.19 What type of sensor is a microphone in IoT devices?
Sound sensor
Motion sensor
Light sensor
Gas sensor
Explanation - Microphones are sound sensors that convert acoustic waves into electrical signals, useful in IoT voice systems.
Correct answer is: Sound sensor
Q.20 Which sensor is best for detecting soil moisture in agriculture IoT?
Thermocouple
Soil moisture sensor
LDR
Barometer
Explanation - Soil moisture sensors help monitor irrigation needs in precision agriculture by detecting water content in soil.
Correct answer is: Soil moisture sensor
Q.21 Which actuator is used in drones to control lift and direction?
Solenoid
Stepper motor
Propeller motor
Relay
Explanation - Propeller motors are actuators that generate thrust and control flight movement in drones.
Correct answer is: Propeller motor
Q.22 What kind of sensor is a gyroscope?
Orientation sensor
Temperature sensor
Gas sensor
Pressure sensor
Explanation - Gyroscopes measure angular velocity, making them orientation sensors in IoT systems.
Correct answer is: Orientation sensor
Q.23 A thermocouple is typically used to measure:
Vibration
Temperature
Light
Pressure
Explanation - Thermocouples generate voltage based on temperature differences, widely used for industrial IoT applications.
Correct answer is: Temperature
Q.24 Which actuator is often used in 3D printers for precise positioning?
Relay
Servo motor
Stepper motor
Solenoid
Explanation - Stepper motors allow precise incremental movements, ideal for 3D printing and CNC machines.
Correct answer is: Stepper motor
Q.25 Which type of sensor is used in smart watches to monitor heart rate?
Photoplethysmography sensor
Accelerometer
Barometer
LDR
Explanation - PPG sensors use light absorption changes to measure heart rate in wearable IoT devices.
Correct answer is: Photoplethysmography sensor