Sensors and Actuator Interfacing — MCQs – EE

1. The main purpose of sensors in an automation system is to:
(A) Detect and measure physical quantities
(B) Generate mechanical motion
(C) Control voltage supply
(D) Store data

2. The main purpose of actuators in a control system is to:
(A) Convert electrical signals into mechanical motion
(B) Measure temperature
(C) Amplify signals
(D) Record data

3. The process of connecting sensors and actuators to a controller is known as:
(A) Interfacing
(B) Multiplexing
(C) Sampling
(D) Modulation

4. An analog sensor provides output in the form of:
(A) Continuous voltage or current signals
(B) Binary logic signals
(C) On/Off pulses only
(D) Digital words

5. A digital sensor provides output in the form of:
(A) Discrete On/Off signals
(B) Continuous voltage
(C) Sinusoidal waveform
(D) Variable frequency

6. A transducer converts:
(A) One form of energy into another
(B) Electrical energy into heat
(C) Mechanical motion into rotation
(D) Analog signals into digital signals only

7. A temperature sensor typically used in industrial applications is:
(A) Thermocouple or RTD
(B) Proximity switch
(C) Potentiometer
(D) Ultrasonic sensor

8. A proximity sensor is used to detect:
(A) The presence or absence of an object
(B) The color of an object
(C) The temperature of a surface
(D) The direction of motion

9. A photoelectric sensor operates using:
(A) Light beam interruption or reflection
(B) Magnetic field detection
(C) Ultrasonic waves
(D) Contact pressure

10. An inductive proximity sensor detects:
(A) Metallic objects
(B) Non-metallic materials
(C) Liquids only
(D) Glass objects

11. A capacitive proximity sensor can detect:
(A) Both metallic and non-metallic objects
(B) Only magnetic materials
(C) Only conductive liquids
(D) Only ferrous materials

12. An ultrasonic sensor measures distance by using:
(A) Sound waves
(B) Light waves
(C) Magnetic fields
(D) Infrared rays

13. A potentiometer is used as a:
(A) Position or displacement sensor
(B) Temperature sensor
(C) Pressure sensor
(D) Flow sensor

14. An LVDT (Linear Variable Differential Transformer) measures:
(A) Linear displacement
(B) Angular velocity
(C) Pressure
(D) Temperature

15. A strain gauge measures:
(A) Force or deformation
(B) Temperature
(C) Flow rate
(D) Voltage

16. A servo motor is used as an actuator for:
(A) Precise position control
(B) Constant speed rotation
(C) Signal amplification
(D) Temperature sensing

17. A stepper motor operates by:
(A) Moving in discrete angular steps
(B) Continuous rotation only
(C) Changing magnetic field direction randomly
(D) Using pneumatic pressure

18. A solenoid actuator converts:
(A) Electrical energy into linear motion
(B) Electrical energy into rotational motion
(C) Magnetic energy into sound
(D) Light into current

19. Signal conditioning in sensor interfacing includes:
(A) Amplification, filtering, and conversion of signals
(B) Power distribution
(C) Data storage
(D) Motor speed control

20. A signal amplifier in sensor interfacing is used to:
(A) Increase weak sensor signals to measurable levels
(B) Reduce power consumption
(C) Convert analog to digital
(D) Delay the output

21. The A/D converter in a control system is used to:
(A) Convert analog sensor signals to digital form
(B) Convert digital data to analog output
(C) Amplify digital signals
(D) Detect logic levels

22. The D/A converter in actuator interfacing is used to:
(A) Convert digital control signals to analog form
(B) Store process data
(C) Filter noise
(D) Convert frequency to voltage

23. The feedback signal from a sensor is used to:
(A) Compare with the reference to correct the process
(B) Start the process
(C) Stop actuator motion
(D) Increase system gain

24. A pneumatic actuator uses:
(A) Compressed air for mechanical motion
(B) Hydraulic oil
(C) Electric current
(D) Magnetic fields

25. A hydraulic actuator uses:
(A) Pressurized fluid to produce motion
(B) Air pressure
(C) Electrical resistance
(D) Magnetic force

26. The interface circuit between a sensor and a microcontroller ensures:
(A) Proper voltage and current matching
(B) Data storage
(C) High-speed communication
(D) Network routing

27. A relay driver circuit is used when:
(A) The actuator requires more current than the controller can supply
(B) The input signal is digital
(C) The system uses only analog inputs
(D) The load is purely resistive

28. The op-amp in a sensor interface is used for:
(A) Amplifying low-level signals
(B) Generating square waves
(C) Power control
(D) Digital switching

29. The signal isolation in interfacing is done using:
(A) Opto-isolators or transformers
(B) Amplifiers only
(C) Diodes
(D) Voltage dividers

30. The main advantage of proper sensor-actuator interfacing is:
(A) Accurate, reliable, and noise-free control operation
(B) Reduced input voltage
(C) Increased wiring complexity
(D) Manual operation