Instrumentation Sensors and Transducers – Multiple Choice Questions & Answers (MCQ4)

The Answers have been provided at the end of the Questions:

Q1. Which of the following sensors is used to measure displacement?

A. Thermistor

B. LVDT

C. Dall tube

D. None of the above

Q2. Which of the below listed sensors is used for temperature measurement?

A. Strain gauge

B. Thermistor

C. Piezoelectric crystal

D. Photodiode

Q3. The transducers that convert a signal into an output signal which is continuous over time are known as?

A. Digital transducers

B. Analog transducers

C. Active transducers

D. Passive transducers

Q4. A LVDT can be used to measure?

A. Force measurement in a beam

B. Vibration measurement

C. Load measurement

D. Angular velocity measurement of a column

Q5. The following sensors are used for measurement of flow, except?

A. Dall tube

B. Piezoelectric crystal

C. Venturi tube

D. Anemometer

Q6. Thermocouples…

A. Require reference junction compensation

B. Are used as temperature transducers

C. Have an output voltage level

D. All of the above

Q7. The following describes the sources of noise in electromagnetic flowmeters, except?

A. Capacitive coupling between signal and power circuits

B. High velocity of fluid

C. Stray voltage in the process liquid

D. Inductive coupling of the magnets within the flowmeter

Q8. What is the function of a digital optical encoder?

A. Translates linear motion into electrical signals

B. It converts motion into a sequence of digital pulses

C. Use to measure mechanical surface tension

D. None of the above

Q9. Which of the below listed devices, best describes a photoconductive device?

A. It is a device that develops an emf in the presence of light.

B. It is a device that changes its resistance with light intensity.

C. It is a device where light generate hole-electron pairs, which causes base current.

D. None of the above.

Q10. A load cell sensor is used to measure?

A. Light intensity

B. Force

C. Viscosity

D. None of the above

Q11. A pitot tube is used to measure?

A. Flow by measuring the rotation of an impeller in the flow.

B. Difference between total and static pressure of a moving liquid.

C. Mass flow rate through U-tube in rotational vibration.

D. The frequency shift of laser light from particles suspended.

Q12. Which statement is true about limit switch?

A. Use light source and photo sensor that detects an object that cuts the light path.

B. Produces voltage in the presence of a magnetic field.

C. Is a mechanical push-button switch mounted in such a way to be actuated when a mechanical part or level gets to the end of travel.

D. None of the above.

Q13. The following sensors are used to measure position, except?

A. LVDT

B. Potentiometer

C. Dall tube

D. Encoder

Q14. Which statement is true about encoders?

A. Position encoders can be grouped into two categories: incremental encoders and absolute encoders.

B. Encoder is a device that provides a digital output as a result of an angular or linear displacement.

C. Incremental encoders detect changes in displacement form some datum position, while absolute encoders give the actual position.

D. All of the above statements are true.

Q15. The following sensors are used in measurement of temperature except?

A. RTDs

B. Thermistor

C. Potentiometer

B. Bimetallic strip

Q16. Absolute pressure is the pressure measured with respect to?

A. Atmospheric pressure

B. Vacuum

C. With respect to another pressure

D. None of the above

Q17. A bourdon tube is used to measure?

A. Flow

B. Force

C. Pressure

D. Density

Q18. Why is the pressure sensor installed above the source in gas pressure measurements?

A. To eliminate errors due to trapped liquid.

B. To eliminate errors due to trapped gas.

C. To eliminate errors due to trapped liquid and gas.

D. None of the above.

Q19. The following devices can be employed in the measurement of pressure, except?

A. Piezoelectric crystals

B. Capacitive devices

C. Barometers

D. Radar devices

Q20. Which of the following statements below is correct about pressure measurement devices?

A. Gauges measure pressure with respect to atmospheric pressure.

B. In a pressure sensor using a diaphragm pressure applied to the diagram causes movement (deformation). This movement can be sensed by strain gauge, piezoelectric techniques.

C. A silicon diaphragm pressure sensor uses silicon which is a semiconductor. This allows strain gauge and amplifier to be integrated in the top surface of the silicon structure after the diaphragm is etched from the backside.

D. All of the above statements are true.

Q21. What feature describes a smart sensor?

A. Smart sensor takes over the signal conditioning and control of the sensor signal, reducing the load on the central control system hence allowing for faster system.

B. Smart sensors have inbuilt diagnostics, which reduces commissioning and start-up costs and also maintenance costs.

C. The setpoint and calibration of a smart sensor are easily changed from the central computer.

D. All the above statements are true.

Q22. The following are devices used for level measurement, except?

A. Sight glass

B. Float sensors

C. Ultrasonic devices

D. Electromagnetic meters

Q23. A displacer uses which technique to measure level?

A. Ultrasonic technology

B. Change in buoyant force on an object

C. Capacitance

D. Differential pressure

Q24. A bubbler device is used to measure?

A. Flow

B. Force

C. Level

D. None of the above

Q25. The statements below are true about the electromagnetic flow sensor, except?

A. The output (voltage) of the sensor is linearly proportional to the flow.

B. There are no obstacles in the flow sensor body which can reduce the pressure.

C. The output is not affected by changes in the characteristics of liquid such as viscosity, pressure and temperature.

D. It can measure non-conductive liquids like hydrocarbons.

Q26. Which statement best describes the hall-effect sensor?

A. It outputs voltage when the magnetic field in which it finds itself increases.

B. Its output voltage depends on the capacitance of the object in vicinity.

C. The output voltage depends on the density of the air.

D. None of the above.

Q27. Which one of the techniques listed below, represent direct level sensing?

 A. Differential pressure level sensors

B. Capacitance level sensing

C. Sight glass

D. None of the above

Q28. The statements below describes a thermocouple sensor except?

A. Is a temperature sensor whose working principle is based on the fact that, metals increase in resistance as temperature rises.

B. Formed by two dissimilar metals joined together to form a junction.

C. The current flowing through the sensor is a result of having two dissimilar metals joined together at different temperatures.

D. It is based on Seebeck effect.

Q29. Which one of the statements below is untrue about position sensors?

A. They measure the physical position of the object.

B. Potentiometers can be used to measure position of an object.

C. The output of optical encoder position sensor is in analogue form.

D. Position sensors can determine velocity by processing that data from the two sequential position samples.

Q30. The technologies listed below are employed in level measurement except?

A. Load sensors

B. Capacitance

C. Ultrasonic ranging

D. Anemometer

Q31. What is a thermopile?

A. An instrument that measures temperature by sensing the heat radiated from a hot body.

B. A number of thermocouples connected in series which increases sensitivity and accuracy by increasing the output voltage when measuring low temperature differences.

C. A resistance temperature detector which uses a sensitive element of extremely pure platinum, copper or nickel wire that provides resistance value at each temperature within its range. 

D. None of the above.

Q32. A tank is filled with pure water. If the pressure at the bottom of the tank is 17.63 psi, what is the depth of the water in meters?

A. 20 m

B. 12.4 m

C. 10 m

D. 11.5 m

Q33. What is the specific gravity of a liquid or solid?

A. This is the weight per unit volume of the material.

B. Density of a material divided by the density of water.

C. It is the mass per unit volume of material.

D. None of the above.

Q34. What is the equivalent of 25 kPa in pounds per square inch (psi)?

A. 7 psi

B. 3.63 psi

C. 4 psi

D. 2.1 psi

Q35. Which type of flowmeters is based on the measuring element sealing off the measuring chamber into series of measuring compartments which are then successively filled and emptied?

A. Vortex flowmeter

B. Mass flowmeter

C. Positive displacement flowmeter

D. Coriolis flowmeter

Q36. What is the resolution of a sensor?

A. It is the measure of the change in the output of an instrument for a change in the measured variable.

B. Refers to the limits within which a signal can be read.

C. The smallest change in a variable which the instrument can respond.

D. None of the above.

Q37. Which of the below listed flowmeters is not a differential type of flowmeter?

A. Venturi meter

B. Pitot tube meter

C. Coriolis meter

D. Orifice meter

Q38. A venturi meter has a meter constant of 0.008 m⁴N^-0.5S^-1. Calculate the flow rate when ΔP = 180 pa.

A. 0.0173 m³/s

B. 13 m³/s

C. 100 m³/s

D. 20 m³/s

Q39. Which of the sensors below can be used for measurement of pressure?

A. LVDT sensor

B. RTD sensor

C. Piezoelectric sensor

D. Thermocouple

Q40. The flowmeters listed below are used for custody transfer, except?

A. Coriolis flowmeters

B. Positive displacement meters

C. Ultrasonic flowmeters

D. Variable area flowmeters

Answers

Q1. B, Q2. B, Q3. B, Q4. A, Q5. B, Q6. D, Q7. B, Q8. C, Q9. B, Q10. B, Q11. B, Q12. C, Q13. C, Q14. D, Q15. C, Q16. B, Q17. C, Q18. B, Q19. D, Q20. D, Q21. D, Q22. D, Q23. B. Q24. C, Q25. D, Q26. A, Q27. C, Q28. A, Q29. C, Q30. D, Q31. B, Q32. B, hint: p =hρg, change pressure into SI unit (pascal) and calculate height), Q33. B, Q34. B, Q35. C, Q36. C, Q37. C, Q38. A, hint: Q = k(ΔP)^0.5 = 0.008x 180^0.5= 0.1073, Q39. C, Q40. D

You can also read: Types of Sensors used in Measurement and Process Control