Q.1 Which transducer converts mechanical pressure into an electrical voltage?
Piezoelectric transducer
Capacitive humidity sensor
Thermocouple
Strain gauge
Explanation - A piezoelectric transducer generates a voltage proportional to the applied mechanical pressure, making it ideal for pressure measurement.
Correct answer is: Piezoelectric transducer
Q.2 A thermocouple produces a voltage due to which phenomenon?
Seebeck effect
Peltier effect
Joule heating
Hall effect
Explanation - The Seebeck effect occurs when two dissimilar conductors are joined at two different temperatures, creating a voltage.
Correct answer is: Seebeck effect
Q.3 Which sensor type is most suitable for measuring liquid levels in a tank?
Ultrasonic sensor
Infrared sensor
Capacitive sensor
Accelerometer
Explanation - Capacitive level sensors detect changes in dielectric constant caused by liquid presence, making them ideal for level measurement.
Correct answer is: Capacitive sensor
Q.4 What is the primary principle behind a Hall effect sensor?
Magnetic field deflects charged particles
Resistive change due to temperature
Capacitance change due to proximity
Light absorption variation
Explanation - The Hall effect sensor measures the voltage generated when a magnetic field passes perpendicular to a current-carrying conductor.
Correct answer is: Magnetic field deflects charged particles
Q.5 A strain gauge is commonly used to measure:
Temperature
Vibration frequency
Mechanical strain
Humidity
Explanation - Strain gauges change resistance when deformed, allowing measurement of strain in structures or materials.
Correct answer is: Mechanical strain
Q.6 Which transducer is best suited for detecting gas concentration?
Optical fiber sensor
Electrochemical sensor
Ultrasonic sensor
Accelerometer
Explanation - Electrochemical sensors produce an electrical signal proportional to gas concentration via chemical reactions.
Correct answer is: Electrochemical sensor
Q.7 What is the output of a linear variable differential transformer (LVDT) when the core is centered?
Maximum output
Zero output
Half of maximum output
Random output
Explanation - At center position, the induced voltages in the secondary windings cancel, producing zero output.
Correct answer is: Zero output
Q.8 Which sensor type uses the change in resistance due to temperature to measure temperature?
Thermocouple
RTD (Resistance Temperature Detector)
Thermistor
Infrared thermometer
Explanation - RTDs change resistance linearly with temperature, providing accurate temperature readings.
Correct answer is: RTD (Resistance Temperature Detector)
Q.9 In a piezoelectric sensor, what happens to the generated voltage when the applied pressure is doubled?
Voltage is halved
Voltage remains the same
Voltage is doubled
Voltage quadruples
Explanation - Piezoelectric materials exhibit a linear relationship between mechanical stress and generated voltage.
Correct answer is: Voltage is doubled
Q.10 Which type of sensor is primarily used for motion detection in security systems?
Inductive proximity sensor
Capacitive humidity sensor
Temperature sensor
Accelerometer
Explanation - Inductive sensors detect metallic objects' presence, commonly used in motion detectors.
Correct answer is: Inductive proximity sensor
Q.11 An optical fiber sensor typically measures changes in:
Temperature via color change
Light intensity or phase shift
Magnetic field strength
Pressure via capacitance
Explanation - Optical fiber sensors detect variations in light properties transmitted through the fiber, such as intensity or phase.
Correct answer is: Light intensity or phase shift
Q.12 What is the main advantage of MEMS accelerometers over piezoelectric accelerometers?
Higher sensitivity
Lower power consumption
Better temperature stability
Higher cost
Explanation - MEMS devices are fabricated using semiconductor processes, enabling low power operation and compact size.
Correct answer is: Lower power consumption
Q.13 Which sensor uses a voltage divider circuit to sense humidity?
Capacitive humidity sensor
Resistive humidity sensor
Optical humidity sensor
Thermal conductivity sensor
Explanation - Capacitive sensors change capacitance with humidity, which can be read using a voltage divider.
Correct answer is: Capacitive humidity sensor
Q.14 A pressure transducer based on a diaphragm is commonly used in:
Temperature measurement
Flow measurement
Force measurement
Light sensing
Explanation - Diaphragm pressure transducers convert fluid pressure into electrical signals for flow calculations.
Correct answer is: Flow measurement
Q.15 Which of the following sensors measures light intensity using the photoconductive effect?
Photodiode
Photoresistor
Photomultiplier tube
Thermopile
Explanation - A photoresistor’s resistance decreases with increased light intensity due to the photoconductive effect.
Correct answer is: Photoresistor
Q.16 What does an IR (infrared) thermometer measure?
Contact temperature
Radiated temperature
Pressure
Humidity
Explanation - IR thermometers detect infrared radiation emitted by objects to determine their temperature without contact.
Correct answer is: Radiated temperature
Q.17 In a LVDT, the phase difference between the two secondary outputs is used to determine:
Temperature
Displacement
Velocity
Acceleration
Explanation - The relative phase and amplitude of the secondary signals provide precise displacement data.
Correct answer is: Displacement
Q.18 Which sensor type is most appropriate for detecting water leaks in pipelines?
Ultrasonic sensor
Resistive temperature sensor
Capacitive humidity sensor
Pressure transducer
Explanation - Capacitive sensors can detect moisture presence, making them suitable for leak detection.
Correct answer is: Capacitive humidity sensor
Q.19 A thermopile sensor operates by:
Measuring magnetic flux changes
Detecting changes in light intensity
Converting thermal radiation into voltage
Measuring pressure changes
Explanation - A thermopile collects infrared energy and converts it to an electrical voltage.
Correct answer is: Converting thermal radiation into voltage
Q.20 Which transducer converts changes in magnetic field into voltage using Faraday’s law?
Hall sensor
Inductive coil sensor
Capacitive sensor
Thermocouple
Explanation - Inductive sensors rely on Faraday’s law to produce voltage when magnetic flux changes.
Correct answer is: Inductive coil sensor
Q.21 A piezoelectric accelerometer is best suited for:
Low-frequency vibration monitoring
High-frequency shock detection
Temperature sensing
Humidity measurement
Explanation - Piezoelectric sensors excel at detecting high-frequency, rapid changes in acceleration.
Correct answer is: High-frequency shock detection
Q.22 Which sensor type is based on the principle of capacitance change due to the distance between two plates?
Capacitive proximity sensor
Inductive sensor
Piezoelectric sensor
Thermocouple
Explanation - Capacitive proximity sensors detect objects by changes in capacitance between plates.
Correct answer is: Capacitive proximity sensor
Q.23 An optical fiber Bragg grating sensor measures:
Temperature only
Strain only
Both temperature and strain
Light intensity
Explanation - Bragg gratings reflect specific wavelengths; shifts indicate temperature and strain variations.
Correct answer is: Both temperature and strain
Q.24 Which of these sensors uses a gas electrode to measure oxygen concentration?
Oxygen sensor (electrochemical)
Optical sensor
Thermistor
Capacitive sensor
Explanation - Electrochemical oxygen sensors convert chemical reactions into electrical signals.
Correct answer is: Oxygen sensor (electrochemical)
Q.25 The most common transducer used in digital thermometers is a:
Thermocouple
RTD
Thermistor
Infrared sensor
Explanation - Thermistors offer high sensitivity and a simple digital interface for temperature measurement.
Correct answer is: Thermistor
Q.26 Which sensor type provides a direct electrical output proportional to water level without any fluid contact?
Capacitive level sensor
Ultrasonic level sensor
Pressure transducer
Thermocouple
Explanation - Ultrasonic sensors send sound pulses and measure return time to determine level.
Correct answer is: Ultrasonic level sensor
Q.27 What is a primary advantage of using a piezoelectric pressure sensor over a strain gauge sensor?
Higher temperature tolerance
Lower cost
Higher sensitivity to pressure changes
Continuous output signal
Explanation - Piezoelectric sensors produce a large voltage change for small pressure variations.
Correct answer is: Higher sensitivity to pressure changes
Q.28 Which of the following is NOT a typical application of a Hall effect sensor?
Position sensing in motors
Speed measurement
Temperature measurement
Current detection
Explanation - Hall sensors detect magnetic fields; they are not used for temperature sensing.
Correct answer is: Temperature measurement
Q.29 In a capacitive humidity sensor, what property of the sensing material changes with humidity?
Conductivity
Dielectric constant
Magnetic permeability
Optical transparency
Explanation - Humidity alters the dielectric constant of the hygroscopic material, changing capacitance.
Correct answer is: Dielectric constant
Q.30 A mass balance transducer in a weighing scale typically uses:
Capacitive plates
Strain gauge
Thermocouple
Optical sensor
Explanation - Strain gauges on the scale beams measure deformation caused by mass.
Correct answer is: Strain gauge
Q.31 Which sensor uses the change in refractive index of a liquid to detect its concentration?
Optical fiber sensor
Capacitive sensor
Inductive sensor
Thermocouple
Explanation - Optical sensors can measure refractive index changes, useful for concentration sensing.
Correct answer is: Optical fiber sensor
Q.32 In a thermocouple, the measured voltage is proportional to:
Temperature difference between junctions
Absolute temperature
Pressure
Magnetic field
Explanation - The thermoelectric voltage depends on the temperature gradient across the junctions.
Correct answer is: Temperature difference between junctions
Q.33 Which sensor type is best suited for measuring vibration frequency?
Accelerometer
Thermocouple
Capacitive humidity sensor
Optical sensor
Explanation - Accelerometers capture acceleration variations, which can be translated into vibration frequency.
Correct answer is: Accelerometer
Q.34 Which transducer produces an output signal that is linear over a wide temperature range?
RTD
Thermistor
Thermocouple
Photoresistor
Explanation - RTDs show a nearly linear resistance change with temperature.
Correct answer is: RTD
Q.35 What is the main limitation of using a piezoelectric sensor for static pressure measurement?
High power consumption
Low frequency response
Inability to measure static pressure
Poor temperature stability
Explanation - Piezoelectric sensors generate voltage only when stress changes; they cannot measure constant pressure.
Correct answer is: Inability to measure static pressure
Q.36 An optical proximity sensor typically detects:
Conductive objects
Magnetic objects
Non-conductive objects
Light intensity changes
Explanation - Optical sensors detect reflected light from both conductive and non-conductive surfaces.
Correct answer is: Non-conductive objects
Q.37 Which of the following sensors operates on the principle of Faraday's induction?
Inductive proximity sensor
Capacitive sensor
Thermocouple
Photodiode
Explanation - Inductive sensors induce voltage in a coil as a metal object moves within its field.
Correct answer is: Inductive proximity sensor
Q.38 What type of sensor would you use to measure the pH of a solution?
pH electrode (glass electrode)
Thermistor
Accelerometer
Capacitive humidity sensor
Explanation - Glass electrodes detect hydrogen ion activity to determine pH.
Correct answer is: pH electrode (glass electrode)
Q.39 Which sensor provides a voltage output proportional to the square of the magnetic field strength?
Hall effect sensor
Fluxgate magnetometer
Magnetostrictive sensor
Inductive coil sensor
Explanation - Fluxgate sensors output a voltage proportional to the magnetic field’s magnitude squared.
Correct answer is: Fluxgate magnetometer
Q.40 What is the operating principle of a gas chromatograph detector?
Ionization of gas molecules
Optical absorption of light
Magnetic flux change
Capacitance change
Explanation - Gas detectors often ionize molecules and measure resulting current.
Correct answer is: Ionization of gas molecules
Q.41 Which transducer converts a change in magnetic flux density into a voltage proportional to the rate of change?
Hall sensor
Inductive coil sensor
Thermocouple
Optical fiber sensor
Explanation - An inductive sensor’s voltage is proportional to dΦ/dt, the change in magnetic flux.
Correct answer is: Inductive coil sensor
Q.42 An LVDT can be used to measure:
Temperature
Pressure
Displacement
Humidity
Explanation - LVDTs are precision displacement transducers based on electromagnetic induction.
Correct answer is: Displacement
Q.43 Which sensor is ideal for detecting the presence of liquid in a pipeline?
Capacitive level sensor
Thermocouple
Accelerometer
Optical sensor
Explanation - Capacitive sensors detect the change in dielectric due to liquid presence.
Correct answer is: Capacitive level sensor
Q.44 What is the main disadvantage of using a resistive temperature detector (RTD) compared to a thermistor?
Lower accuracy
Higher cost
Higher temperature drift
Longer response time
Explanation - RTDs are made of precious metals like platinum, increasing cost relative to thermistors.
Correct answer is: Higher cost
Q.45 Which sensor uses the Seebeck effect to generate voltage?
Thermocouple
Capacitive humidity sensor
Hall sensor
Strain gauge
Explanation - Thermocouples produce voltage from temperature gradients via the Seebeck effect.
Correct answer is: Thermocouple
Q.46 Which transducer is best suited for high temperature applications?
Thermocouple
Thermistor
Capacitive sensor
Inductive sensor
Explanation - Thermocouples maintain accuracy at temperatures beyond 1000 °C.
Correct answer is: Thermocouple
Q.47 A magnetic reed switch operates based on:
Capacitance change
Magnetically actuated contacts
Temperature variation
Optical reflection
Explanation - Reed switches close or open when a magnetic field brings the reed together.
Correct answer is: Magnetically actuated contacts
Q.48 Which of the following sensors measures the speed of a rotating shaft without contact?
Laser tachometer
Hall effect sensor
Thermocouple
Capacitive sensor
Explanation - Laser tachometers use reflected laser light to calculate rotational speed.
Correct answer is: Laser tachometer
Q.49 In a capacitive pressure sensor, the capacitance changes due to:
Dielectric constant change
Physical separation of plates
Temperature of the plates
Magnetic field
Explanation - Pressure changes the distance between plates, altering capacitance.
Correct answer is: Physical separation of plates
Q.50 Which sensor type is used to detect the presence of a metal object in an automated sorting system?
Inductive proximity sensor
Capacitive sensor
Thermocouple
Optical sensor
Explanation - Inductive sensors sense metallic objects through magnetic field changes.
Correct answer is: Inductive proximity sensor
Q.51 Which of the following is a key parameter measured by a flow transducer using a turbine?
Velocity of fluid
Temperature of fluid
Pressure of fluid
Magnetic field of fluid
Explanation - A turbine flow meter measures fluid velocity by counting the rotations of a rotor.
Correct answer is: Velocity of fluid
Q.52 A MEMS gyroscope measures:
Angular velocity
Acceleration
Temperature
Light intensity
Explanation - MEMS gyroscopes detect rotation rates using vibrating structures.
Correct answer is: Angular velocity
Q.53 What is the primary advantage of using an optical fiber sensor over a conventional electrical sensor for high voltage environments?
Higher sensitivity
Electrical isolation
Lower cost
Smaller size
Explanation - Optical fibers do not conduct electricity, providing safe measurement in high voltage settings.
Correct answer is: Electrical isolation
Q.54 Which sensor type typically uses a vibrating quartz crystal to measure pressure?
Piezoelectric sensor
Capacitive sensor
Thermocouple
Optical sensor
Explanation - Piezoelectric crystals change electrical charge under stress, useful for pressure sensing.
Correct answer is: Piezoelectric sensor
Q.55 A photodiode is primarily used to detect:
Magnetic fields
Light
Temperature
Pressure
Explanation - Photodiodes generate current when photons strike their semiconductor material.
Correct answer is: Light
Q.56 Which of the following sensors can detect both humidity and temperature simultaneously?
Capacitive humidity sensor with built-in temperature compensation
Thermocouple
Inductive sensor
Piezoelectric sensor
Explanation - Many modern capacitive humidity sensors include temperature compensation for accurate readings.
Correct answer is: Capacitive humidity sensor with built-in temperature compensation
Q.57 What is the key benefit of using a pressure transducer with a Wheatstone bridge configuration?
Increased sensitivity
Simplified wiring
Higher temperature tolerance
Automatic calibration
Explanation - Wheatstone bridges balance small changes in resistance, enhancing sensitivity to pressure-induced strain.
Correct answer is: Increased sensitivity
Q.58 Which sensor type is most suitable for measuring the speed of a vehicle?
Pitot tube
Doppler radar sensor
Capacitive sensor
Thermistor
Explanation - Doppler radar sensors detect velocity via frequency shift of reflected radar waves.
Correct answer is: Doppler radar sensor
Q.59 In a temperature sensor using a thermistor, the resistance typically changes with temperature following which relationship?
Directly proportional
Inverse proportional
Exponential
Logarithmic
Explanation - NTC thermistors have resistance that decreases exponentially as temperature rises.
Correct answer is: Inverse proportional
Q.60 Which type of sensor can measure the composition of gases in a mixture?
Mass spectrometer
Optical fiber sensor
Thermistor
Capacitive humidity sensor
Explanation - Mass spectrometers separate gas ions by mass-to-charge ratio, revealing composition.
Correct answer is: Mass spectrometer
Q.61 Which sensor operates based on the change in refractive index when light passes through it?
Fiber Bragg grating sensor
Capacitive sensor
Hall sensor
Accelerometer
Explanation - Bragg gratings reflect specific wavelengths; strain changes the refractive index, shifting the wavelength.
Correct answer is: Fiber Bragg grating sensor
Q.62 A piezoelectric accelerometer is particularly useful for detecting:
Static acceleration
High-frequency vibrations
Temperature gradients
Pressure changes
Explanation - Piezoelectric materials respond quickly to rapid acceleration changes, ideal for high-frequency signals.
Correct answer is: High-frequency vibrations
Q.63 What is the primary measurement principle of an ultrasonic level sensor?
Time of flight of sound pulse
Change in capacitance
Magnetic field detection
Electrical resistance change
Explanation - Ultrasonic sensors send a pulse and measure the time until echo returns to determine distance.
Correct answer is: Time of flight of sound pulse
Q.64 Which transducer uses the Faraday effect to measure magnetic fields?
Hall effect sensor
Faraday rotator sensor
Thermocouple
Optical fiber sensor
Explanation - Faraday rotators rotate the polarization of light in a magnetic field, enabling field measurement.
Correct answer is: Faraday rotator sensor
Q.65 Which sensor is typically employed to measure atmospheric pressure in weather stations?
Bourdon tube pressure gauge
Capacitive pressure sensor
Strain gauge pressure sensor
Barometric pressure transducer
Explanation - Barometric transducers convert atmospheric pressure into electrical signals for weather monitoring.
Correct answer is: Barometric pressure transducer
Q.66 The output of a thermistor is often linearized by using:
Voltage divider
Wheatstone bridge
Op-amp filter
Temperature compensation circuit
Explanation - A bridge arrangement helps linearize the non-linear resistance-temperature relationship of a thermistor.
Correct answer is: Wheatstone bridge
Q.67 Which of the following sensors is most commonly used in automotive ABS (Anti-lock Braking System)?
Hall effect sensor
Piezoelectric sensor
Capacitive sensor
Thermocouple
Explanation - ABS systems use Hall sensors to detect wheel rotation speed for braking control.
Correct answer is: Hall effect sensor
Q.68 What is the key difference between a capacitive sensor and a resistive sensor?
Capacitive sensors measure voltage; resistive sensors measure current
Capacitive sensors rely on dielectric change; resistive sensors rely on conductivity change
Capacitive sensors are for high temperature; resistive sensors are for low temperature
Capacitive sensors use magnetic fields; resistive sensors use electric fields
Explanation - Capacitive sensors detect changes in capacitance, while resistive sensors detect changes in resistance.
Correct answer is: Capacitive sensors rely on dielectric change; resistive sensors rely on conductivity change
Q.69 Which sensor type is best for measuring the direction of a magnetic field vector?
Fluxgate magnetometer
Hall effect sensor
Inductive coil sensor
Thermocouple
Explanation - Fluxgate sensors provide vectorial magnetic field measurements.
Correct answer is: Fluxgate magnetometer
Q.70 In an infrared gas sensor, what principle is used to detect gas molecules?
Absorption of specific infrared wavelengths
Reflection of infrared light
Emission of infrared radiation
Capacitive change
Explanation - IR gas sensors measure the attenuation of infrared light at wavelengths absorbed by target gases.
Correct answer is: Absorption of specific infrared wavelengths
Q.71 Which transducer uses a vibrating quartz crystal to measure acoustic pressure?
Piezoelectric transducer
Capacitive sensor
Optical sensor
Thermistor
Explanation - The vibration of quartz in piezoelectric materials generates voltage proportional to acoustic pressure.
Correct answer is: Piezoelectric transducer
Q.72 Which sensor is commonly used to measure the humidity inside a sealed chamber?
Capacitive humidity sensor
Thermocouple
Hall sensor
Accelerometer
Explanation - Capacitive sensors provide reliable humidity measurement in controlled environments.
Correct answer is: Capacitive humidity sensor
Q.73 What type of transducer would be best for measuring the vibration of a bridge deck?
Strain gauge
Accelerometer
Thermocouple
Capacitive sensor
Explanation - Accelerometers capture dynamic vibration data from structures.
Correct answer is: Accelerometer
Q.74 Which of the following is an advantage of a capacitive pressure sensor over a piezoelectric pressure sensor?
Higher dynamic range
Continuous output for static pressure
Lower cost
Higher temperature tolerance
Explanation - Capacitive sensors can measure static pressure, while piezoelectric sensors only respond to changes.
Correct answer is: Continuous output for static pressure
Q.75 Which sensor type is commonly used for detecting the presence of a magnetic field in an MRI machine?
Hall effect sensor
Capacitive sensor
Thermistor
Optical sensor
Explanation - Hall sensors provide non-contact magnetic field measurement essential in MRI environments.
Correct answer is: Hall effect sensor
Q.76 A photoconductive cell is best used for measuring:
Temperature
Light intensity
Pressure
Humidity
Explanation - Photoconductive cells change resistance with light intensity, making them suitable for photometry.
Correct answer is: Light intensity
Q.77 What is the primary purpose of a fluxgate sensor in industrial automation?
Temperature measurement
Magnetic field sensing
Pressure measurement
Humidity measurement
Explanation - Fluxgate sensors provide accurate magnetic field measurements for position and velocity control.
Correct answer is: Magnetic field sensing
Q.78 Which type of sensor is best suited for measuring the velocity of a liquid in a pipe?
Ultrasonic flow sensor
Thermocouple
Capacitive sensor
Accelerometer
Explanation - Ultrasonic sensors use time-of-flight differences to calculate flow velocity.
Correct answer is: Ultrasonic flow sensor
Q.79 The sensitivity of a piezoelectric sensor is defined as:
Voltage output per unit pressure
Resistance change per unit temperature
Capacitance change per unit distance
Current output per unit magnetic field
Explanation - Piezoelectric sensitivity is measured as the generated voltage per unit of applied pressure.
Correct answer is: Voltage output per unit pressure
Q.80 Which sensor type would be most appropriate for detecting the presence of a gas leak in a chemical plant?
Electrochemical sensor
Capacitive humidity sensor
Accelerometer
Thermistor
Explanation - Electrochemical sensors detect gas molecules by chemical reactions producing a measurable signal.
Correct answer is: Electrochemical sensor
Q.81 A pressure sensor based on a diaphragm typically uses which type of transduction mechanism?
Capacitive
Resistive
Optical
Magnetic
Explanation - Diaphragm deflection changes the gap between plates, altering capacitance to sense pressure.
Correct answer is: Capacitive
Q.82 Which type of sensor would be used to measure the depth of water in a reservoir without contacting the water?
Ultrasonic level sensor
Capacitive sensor
Thermistor
Hall sensor
Explanation - Ultrasonic level sensors use sound waves to detect water depth without contact.
Correct answer is: Ultrasonic level sensor
Q.83 Which sensor uses a vibrating element to produce an electrical signal proportional to acceleration?
Piezoelectric accelerometer
Thermocouple
Capacitive sensor
Infrared sensor
Explanation - Piezoelectric accelerometers generate voltage in response to mechanical vibrations.
Correct answer is: Piezoelectric accelerometer
Q.84 What is the main advantage of MEMS-based sensors in instrumentation?
High power consumption
Large size
Low cost and mass production
Low integration capability
Explanation - MEMS fabrication uses semiconductor processes, enabling low-cost, high-volume production.
Correct answer is: Low cost and mass production
Q.85 A temperature sensor that provides an output voltage proportional to temperature difference is known as a:
Thermocouple
Thermistor
RTD
Infrared thermometer
Explanation - Thermocouples produce voltage based on the temperature gradient between junctions.
Correct answer is: Thermocouple
Q.86 Which type of sensor is most suitable for detecting the presence of metal in a conveyor belt system?
Inductive proximity sensor
Capacitive sensor
Accelerometer
Thermocouple
Explanation - Inductive sensors sense metal objects through magnetic field disturbances.
Correct answer is: Inductive proximity sensor
Q.87 Which sensor type is commonly used to monitor the vibration of an industrial machine?
Strain gauge
Accelerometer
Thermocouple
Capacitive sensor
Explanation - Accelerometers provide real-time vibration data for predictive maintenance.
Correct answer is: Accelerometer
Q.88 What is the typical output of a Hall effect sensor in a DC motor for speed measurement?
Analog voltage proportional to speed
Digital pulses per revolution
Temperature reading
Pressure reading
Explanation - Hall sensors generate pulses as the rotor passes, providing speed data.
Correct answer is: Digital pulses per revolution
Q.89 Which sensor is used to measure the pH of a solution?
Glass electrode pH sensor
Thermistor
Capacitive humidity sensor
Thermocouple
Explanation - Glass electrodes measure hydrogen ion activity for pH determination.
Correct answer is: Glass electrode pH sensor
Q.90 What is a primary disadvantage of using a thermistor for temperature measurement in a high-accuracy system?
Nonlinearity
High cost
Slow response
Limited temperature range
Explanation - Thermistors exhibit a highly nonlinear resistance-temperature relationship.
Correct answer is: Nonlinearity
Q.91 Which sensor type can detect the presence of a dielectric material in close proximity?
Capacitive proximity sensor
Inductive proximity sensor
Thermocouple
Accelerometer
Explanation - Capacitive sensors sense dielectric changes due to nearby objects.
Correct answer is: Capacitive proximity sensor
Q.92 Which transducer provides a direct electrical signal proportional to fluid pressure?
Pressure transducer
Flow meter
Temperature sensor
Humidity sensor
Explanation - Pressure transducers convert fluid pressure into electrical output.
Correct answer is: Pressure transducer
Q.93 Which type of sensor is typically used for measuring the position of a shaft in a robotic arm?
Encoders (optical or magnetic)
Thermocouple
Capacitive sensor
Accelerometer
Explanation - Encoders provide precise position feedback for robotic control.
Correct answer is: Encoders (optical or magnetic)
Q.94 Which sensor type uses a vibrating quartz crystal to detect changes in mass?
Quartz crystal microbalance (QCM)
Capacitive sensor
Thermocouple
Piezoelectric sensor
Explanation - QCM measures frequency shift due to mass loading on a quartz crystal.
Correct answer is: Quartz crystal microbalance (QCM)
Q.95 What is the main principle behind an optical fiber sensor for strain measurement?
Change in light intensity
Change in polarization
Change in wavelength (Bragg reflection)
Change in temperature
Explanation - Strain causes a shift in the Bragg wavelength reflected from the fiber grating.
Correct answer is: Change in wavelength (Bragg reflection)
Q.96 Which sensor is commonly used in HVAC systems to monitor humidity?
Capacitive humidity sensor
Thermocouple
Accelerometer
Capacitive pressure sensor
Explanation - Capacitive humidity sensors are inexpensive and provide reliable humidity readings.
Correct answer is: Capacitive humidity sensor
Q.97 Which transducer is best suited for high-speed flow measurement in gas pipelines?
Turbine flow meter
Coriolis flow meter
Ultrasonic flow meter
Capacitive flow sensor
Explanation - Ultrasonic meters accurately measure high-speed gas flows non-invasively.
Correct answer is: Ultrasonic flow meter
Q.98 Which sensor is used to detect the presence of a metal rod in an automated assembly line?
Inductive proximity sensor
Capacitive sensor
Thermocouple
Accelerometer
Explanation - Inductive sensors are ideal for detecting metal objects in industrial automation.
Correct answer is: Inductive proximity sensor
Q.99 Which type of sensor would be most appropriate for measuring temperature inside a high-temperature furnace?
Thermocouple
RTD
Thermistor
Capacitive humidity sensor
Explanation - Thermocouples maintain accuracy and durability at very high temperatures.
Correct answer is: Thermocouple
Q.100 What is the output characteristic of a capacitive humidity sensor?
Resistance changes with humidity
Capacitance changes with humidity
Voltage changes with humidity
Current changes with humidity
Explanation - The dielectric constant of the hygroscopic material changes with moisture, altering capacitance.
Correct answer is: Capacitance changes with humidity
Q.101 Which sensor type would be used to measure the velocity of a moving vehicle?
Doppler radar sensor
Thermocouple
Capacitive sensor
Accelerometer
Explanation - Doppler radar measures speed through frequency shift of reflected radio waves.
Correct answer is: Doppler radar sensor
Q.102 What is the primary advantage of using a fiber optic sensor for temperature measurement?
Electrical insulation
High sensitivity
Low cost
Small size
Explanation - Fiber optics are immune to electromagnetic interference, ideal for harsh environments.
Correct answer is: Electrical insulation
Q.103 Which transducer type can be used to measure acceleration in a seismic monitoring system?
Accelerometer
Thermocouple
Capacitive humidity sensor
Infrared sensor
Explanation - Seismic sensors are accelerometers that detect ground motion.
Correct answer is: Accelerometer
Q.104 Which sensor would be best for measuring the level of a liquid in a tank with corrosive contents?
Ultrasonic level sensor
Capacitive level sensor
Pressure transducer
Thermocouple
Explanation - Ultrasonic sensors do not contact the liquid, reducing corrosion risk.
Correct answer is: Ultrasonic level sensor
Q.105 The output of a thermocouple is proportional to:
Temperature difference between its junctions
Absolute temperature
Pressure
Magnetic field
Explanation - Thermocouples produce voltage based on the temperature gradient across the junctions.
Correct answer is: Temperature difference between its junctions
Q.106 What type of sensor is used to detect the presence of a gas in industrial safety systems?
Electrochemical sensor
Capacitive humidity sensor
Thermistor
Inductive sensor
Explanation - Electrochemical sensors generate a signal from the reaction of gas molecules with a sensor electrode.
Correct answer is: Electrochemical sensor
Q.107 Which sensor type is commonly used to measure the vibration of a bridge deck?
Strain gauge
Accelerometer
Thermocouple
Capacitive sensor
Explanation - Accelerometers provide real‑time vibration data for structural monitoring.
Correct answer is: Accelerometer
Q.108 Which transducer is used for measuring the flow of liquids in pipelines?
Turbine flow meter
Capacitive flow sensor
Thermistor
Accelerometer
Explanation - Turbine flow meters measure liquid velocity by counting rotations of a rotor.
Correct answer is: Turbine flow meter
Q.109 Which sensor type can measure the displacement of a shaft in a machine?
Linear variable differential transformer (LVDT)
Thermocouple
Capacitive humidity sensor
Accelerometer
Explanation - LVDTs provide precise, non‑contact displacement measurements.
Correct answer is: Linear variable differential transformer (LVDT)
Q.110 What is the main advantage of using a MEMS accelerometer over a piezoelectric accelerometer?
Higher sensitivity to low frequencies
Lower power consumption
Higher temperature tolerance
Higher cost
Explanation - MEMS accelerometers use semiconductor fabrication, resulting in lower power usage.
Correct answer is: Lower power consumption
Q.111 Which sensor uses a vibrating quartz crystal to generate an electrical signal proportional to acoustic pressure?
Piezoelectric transducer
Capacitive sensor
Optical sensor
Thermistor
Explanation - Piezoelectric crystals produce voltage in response to mechanical stress, including acoustic waves.
Correct answer is: Piezoelectric transducer
Q.112 What type of sensor is most commonly used to detect the presence of metal in a conveyor belt system?
Inductive proximity sensor
Capacitive sensor
Accelerometer
Thermocouple
Explanation - Inductive sensors detect metallic objects through changes in magnetic field.
Correct answer is: Inductive proximity sensor
Q.113 Which transducer can be used to measure the level of a liquid in a tank by measuring the time-of-flight of an ultrasonic pulse?
Ultrasonic level sensor
Capacitive level sensor
Pressure transducer
Thermocouple
Explanation - Ultrasonic level sensors rely on the travel time of an ultrasonic pulse to determine liquid level.
Correct answer is: Ultrasonic level sensor
Q.114 What is the primary function of a strain gauge in a structural health monitoring system?
Measure temperature
Measure strain
Measure pressure
Measure humidity
Explanation - Strain gauges change resistance when deformed, providing a direct measure of strain.
Correct answer is: Measure strain
Q.115 Which sensor type is best suited for detecting the presence of a gas leak in a chemical plant?
Electrochemical sensor
Capacitive humidity sensor
Accelerometer
Thermistor
Explanation - Electrochemical sensors detect specific gases by measuring the resulting electrical current from a chemical reaction.
Correct answer is: Electrochemical sensor
Q.116 What is the principle of operation of an ultrasonic flow meter?
Measuring changes in electrical resistance
Measuring changes in sound speed
Measuring changes in magnetic field
Measuring changes in capacitance
Explanation - Ultrasonic flow meters use transit-time differences of ultrasonic pulses to determine flow velocity.
Correct answer is: Measuring changes in sound speed
Q.117 Which transducer is used to measure acceleration in aerospace applications?
Piezoelectric accelerometer
Thermocouple
Capacitive sensor
Optical sensor
Explanation - Piezoelectric accelerometers provide high-frequency acceleration data needed for flight dynamics.
Correct answer is: Piezoelectric accelerometer
Q.118 Which sensor would be most appropriate for measuring the level of a liquid in a tank that contains corrosive chemicals?
Ultrasonic level sensor
Capacitive level sensor
Pressure transducer
Thermocouple
Explanation - Ultrasonic sensors do not contact the liquid, minimizing corrosion effects.
Correct answer is: Ultrasonic level sensor
Q.119 What type of sensor is used to measure the temperature of a high‑temperature furnace?
Thermocouple
RTD
Thermistor
Capacitive humidity sensor
Explanation - Thermocouples maintain accuracy at temperatures beyond 1000 °C, suitable for furnaces.
Correct answer is: Thermocouple
Q.120 Which transducer is commonly used to measure the displacement of a shaft in a robotic arm?
Encoders (optical or magnetic)
Thermocouple
Capacitive sensor
Accelerometer
Explanation - Encoders provide precise position feedback for robotic applications.
Correct answer is: Encoders (optical or magnetic)
Q.121 What is the main principle behind a Hall effect sensor?
Deflection of a magnetic field
Change in capacitance due to proximity
Change in resistance due to temperature
Absorption of infrared light
Explanation - Hall sensors generate a voltage when a magnetic field is applied perpendicular to a current carrying conductor.
Correct answer is: Deflection of a magnetic field
Q.122 Which sensor type is most suitable for detecting the presence of a metal rod in an automated assembly line?
Inductive proximity sensor
Capacitive sensor
Thermistor
Accelerometer
Explanation - Inductive sensors sense metallic objects through magnetic field disturbances.
Correct answer is: Inductive proximity sensor
Q.123 What is the output of a photodiode when it is illuminated?
Voltage proportional to light intensity
Current proportional to light intensity
Resistance inversely proportional to light intensity
Capacitance proportional to light intensity
Explanation - Photodiodes produce a photocurrent that is proportional to incident light intensity.
Correct answer is: Current proportional to light intensity
Q.124 Which transducer is commonly used to measure the velocity of a moving vehicle?
Doppler radar sensor
Thermocouple
Capacitive sensor
Accelerometer
Explanation - Doppler radar sensors measure speed through frequency shift of reflected radio waves.
Correct answer is: Doppler radar sensor
Q.125 Which sensor type is best suited for measuring the temperature of a high‑temperature furnace?
Thermocouple
RTD
Thermistor
Capacitive humidity sensor
Explanation - Thermocouples maintain accuracy at temperatures beyond 1000 °C, suitable for furnaces.
Correct answer is: Thermocouple
Q.126 Which of the following sensors can detect both humidity and temperature simultaneously?
Capacitive humidity sensor with built‑in temperature compensation
Thermocouple
Inductive sensor
Piezoelectric sensor
Explanation - Many modern capacitive humidity sensors include temperature compensation for accurate readings.
Correct answer is: Capacitive humidity sensor with built‑in temperature compensation
Q.127 What is the key benefit of MEMS-based sensors in instrumentation?
High power consumption
Large size
Low cost and mass production
Low integration capability
Explanation - MEMS fabrication uses semiconductor processes, enabling low-cost, high-volume production.
Correct answer is: Low cost and mass production
Q.128 Which sensor would be most appropriate for measuring the level of a liquid in a tank that contains corrosive chemicals?
Ultrasonic level sensor
Capacitive level sensor
Pressure transducer
Thermocouple
Explanation - Ultrasonic sensors do not contact the liquid, minimizing corrosion risk.
Correct answer is: Ultrasonic level sensor
Q.129 What is the principle behind a thermistor?
Change in resistance with temperature
Change in voltage with pressure
Change in capacitance with humidity
Change in inductance with magnetic field
Explanation - Thermistors exhibit a temperature-dependent resistance change, used for temperature sensing.
Correct answer is: Change in resistance with temperature
Q.130 Which transducer is best suited for measuring the velocity of a gas in a pipeline?
Coriolis flow meter
Ultrasonic flow meter
Turbine flow meter
Capacitive flow sensor
Explanation - Ultrasonic flow meters are accurate for measuring high-speed gas flows non‑invasively.
Correct answer is: Ultrasonic flow meter
Q.131 Which type of sensor is commonly used for measuring the vibration of a bridge deck?
Strain gauge
Accelerometer
Thermocouple
Capacitive sensor
Explanation - Accelerometers capture dynamic vibration data for structural monitoring.
Correct answer is: Accelerometer
Q.132 Which sensor type can measure the pressure of a fluid in a pipe?
Pressure transducer
Flow meter
Temperature sensor
Humidity sensor
Explanation - Pressure transducers convert fluid pressure into an electrical signal.
Correct answer is: Pressure transducer
Q.133 Which sensor type is commonly used in HVAC systems to monitor humidity?
Capacitive humidity sensor
Thermocouple
Accelerometer
Capacitive pressure sensor
Explanation - Capacitive humidity sensors are inexpensive and provide reliable humidity readings.
Correct answer is: Capacitive humidity sensor
Q.134 What type of sensor would be used to measure the velocity of a moving vehicle?
Doppler radar sensor
Thermocouple
Capacitive sensor
Accelerometer
Explanation - Doppler radar sensors measure speed through frequency shift of reflected radio waves.
Correct answer is: Doppler radar sensor
Q.135 What is the main disadvantage of using a thermistor in a high‑accuracy temperature system?
Nonlinearity
High cost
Slow response
Limited temperature range
Explanation - Thermistors exhibit a highly nonlinear resistance‑temperature relationship.
Correct answer is: Nonlinearity
Q.136 Which type of sensor can detect the presence of a dielectric material in close proximity?
Capacitive proximity sensor
Inductive proximity sensor
Thermocouple
Accelerometer
Explanation - Capacitive sensors sense dielectric changes due to nearby objects.
Correct answer is: Capacitive proximity sensor
Q.137 What is the main principle behind a pressure sensor using a diaphragm?
Capacitance change between plates
Resistance change due to strain
Voltage change due to magnetic field
Temperature change due to pressure
Explanation - Diaphragm deflection changes the gap between plates, altering capacitance for pressure sensing.
Correct answer is: Capacitance change between plates
Q.138 Which transducer type can be used to measure displacement of a shaft?
Linear variable differential transformer (LVDT)
Thermocouple
Capacitive humidity sensor
Accelerometer
Explanation - LVDTs provide precise, non‑contact displacement measurements.
Correct answer is: Linear variable differential transformer (LVDT)
Q.139 Which sensor type is commonly used to measure the strain in a bridge?
Strain gauge
Accelerometer
Thermocouple
Capacitive sensor
Explanation - Strain gauges directly measure deformation by resistance change.
Correct answer is: Strain gauge
Q.140 Which sensor is used to detect the presence of a magnetic field in an MRI machine?
Hall effect sensor
Capacitive sensor
Thermistor
Optical sensor
Explanation - Hall sensors provide non‑contact magnetic field measurement essential in MRI environments.
Correct answer is: Hall effect sensor
Q.141 Which transducer provides a direct electrical signal proportional to fluid pressure?
Pressure transducer
Flow meter
Temperature sensor
Humidity sensor
Explanation - Pressure transducers convert fluid pressure into an electrical output.
Correct answer is: Pressure transducer
Q.142 What is the principle of operation of a Hall effect sensor?
Change in capacitance due to proximity
Deflection of a magnetic field
Change in resistance due to temperature
Absorption of infrared light
Explanation - Hall sensors generate a voltage when a magnetic field is applied perpendicular to a current carrying conductor.
Correct answer is: Deflection of a magnetic field
Q.143 Which sensor would be most appropriate for measuring the level of a liquid in a tank that contains corrosive chemicals?
Ultrasonic level sensor
Capacitive level sensor
Pressure transducer
Thermocouple
Explanation - Ultrasonic sensors do not contact the liquid, minimizing corrosion risk.
Correct answer is: Ultrasonic level sensor
Q.144 What is the main function of a strain gauge in a structural health monitoring system?
Measure temperature
Measure strain
Measure pressure
Measure humidity
Explanation - Strain gauges change resistance when deformed, providing a direct measure of strain.
Correct answer is: Measure strain
Q.145 Which transducer can be used to measure the flow of liquids in pipelines?
Turbine flow meter
Capacitive flow sensor
Thermistor
Accelerometer
Explanation - Turbine flow meters measure liquid velocity by counting rotations of a rotor.
Correct answer is: Turbine flow meter
Q.146 What type of sensor is commonly used to measure the vibration of a bridge deck?
Strain gauge
Accelerometer
Thermocouple
Capacitive sensor
Explanation - Accelerometers capture dynamic vibration data for structural monitoring.
Correct answer is: Accelerometer
Q.147 Which sensor type can measure the pressure of a fluid in a pipe?
Pressure transducer
Flow meter
Temperature sensor
Humidity sensor
Explanation - Pressure transducers convert fluid pressure into an electrical signal.
Correct answer is: Pressure transducer
Q.148 Which sensor type is commonly used in HVAC systems to monitor humidity?
Capacitive humidity sensor
Thermocouple
Accelerometer
Capacitive pressure sensor
Explanation - Capacitive humidity sensors are inexpensive and provide reliable humidity readings.
Correct answer is: Capacitive humidity sensor
Q.149 What type of sensor would be used to measure the velocity of a moving vehicle?
Doppler radar sensor
Thermocouple
Capacitive sensor
Accelerometer
Explanation - Doppler radar sensors measure speed through frequency shift of reflected radio waves.
Correct answer is: Doppler radar sensor