Free Process Control and Instrumentation MCQs with Answers
254 Process Control and Instrumentation MCQs from Chemical Engineering, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
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254 questions · page 13 of 13
- A. Passive
- B. Active
- C. Capacitive
- D. None of these
Explanation: An LVDT needs an external AC excitation source to produce its output signal, so it is a passive transducer.
Correct answer: Passive- A. Compact & rugged construction with an accuracy of 0.1 to 1%
- B. All A, B & C
- C. Provision of thermal compensation and is hermetically sealed
- D. No moving parts and incurs negligible deflection under load
Explanation: A practical load cell is compact and rugged, has no significant moving parts, and is commonly temperature-compensated and hermetically…
Correct answer: All A, B & C243. The following thermocouple may be used for measuring temperature upto 1873°K__________________?
- A. Chromel-alumel
- B. Copper-constantan
- C. Platinum-platinum rhodium
- D. Iron-constantan
Explanation: A platinum-platinum-rhodium thermocouple, commonly Type R or Type S, is suitable for very high temperatures approaching 1873 K.
Correct answer: Platinum-platinum rhodium- A. The continuous adjustment of the set point index of an automatic control loop by a primary(master) controller
- B. Used when changes in process conditions cause serious upsets in the controlled variable
- C. Useful to control flow from temperature
- D. All A, B & C
Explanation: In cascade control, a primary controller continuously changes the set point of a secondary controller.
Correct answer: All A, B & C- A. Frequency
- B. Amplitude
- C. Damping
- D. None of these
Explanation: A Lissajous figure compares an unknown periodic signal with a reference signal, allowing the frequency ratio to be found from the plotted…
Correct answer: Frequency- A. Linear variable differential transducer (LVDT)
- B. Shaft encoder
- C. Stroboscope
- D. Tachometer
Explanation: A shaft encoder converts angular position or rotation into electrical pulses or coded signals, allowing direct measurement of angular…
Correct answer: Shaft encoder- A. Capacitance
- B. Resistance
- C. None of these
- D. Mutual inductance
Explanation: An LVDT has a movable ferromagnetic core that changes the mutual inductance between its primary and secondary coils.
Correct answer: Mutual inductance- A. Final control element
- B. On-off control
- C. Floating control action
- D. None of these
Explanation: The final control element receives the controller output and physically changes the manipulated variable, such as a valve changing fluid…
Correct answer: Final control element- A. Derivative time
- B. Deviation
- C. Error ratio
- D. Differential gap
Explanation: Deviation is the instantaneous difference between the set point and the controlled variable, with its sign depending on the convention…
Correct answer: Deviation- A. Steel
- B. Copper
- C. Aluminium
- D. Brass
Explanation: Copper conducts heat much better than steel, aluminium, or brass, so the thermal well reaches the gas temperature with less temperature…
Correct answer: Copper- A. Gamma rays
- B. Microwaves
- C. A beam of coherent light
- D. A beam of white light
Explanation: A laser uses stimulated emission to generate light waves having a fixed phase relationship, giving a coherent beam.
Correct answer: A beam of coherent light252. ______________ circuit is most commonly used to measure strain with the help of a strain gauge?
- A. Ballast
- B. Voltage balancing potentiometric
- C. Simple current sensitive
- D. None of these
Explanation: Strain gauges are commonly connected in a Wheatstone-bridge arrangement, often operated as a voltage-balancing circuit so very small…
Correct answer: Voltage balancing potentiometric- A. Piezoelectric
- B. Preloaded spring
- C. Bonded strain gauge
- D. None of these
Explanation: Piezoelectric accelerometers are well suited to very high-frequency vibration because their stiff sensing elements have a broad…
Correct answer: Piezoelectric- A. Frequency counter
- B. Tachometer
- C. Strobometer
- D. Speedometer
Explanation: A strobometer determines rotational speed from the stationary image produced when flashing frequency matches the shaft speed, allowing…
Correct answer: Strobometer