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 7 of 13
- A. Gage as well as vacuum
- B. Absolute as well as differential
- C. Neither A. nor B.
- D. Both A. and B.
Explanation: Strain-gage transducers can be arranged to measure gauge, vacuum, absolute, or differential pressure, depending on their reference and…
Correct answer: Both A. and B.- A. -1
- B. 0
- C. 1
- D. ∞
Explanation: A pole is a value of s at which the transfer function becomes unbounded, so G(s) approaches infinity.
Correct answer: ∞- A. Gauge
- B. Atmospheric
- C. Vacuum
- D. Absolute
Explanation: A mercury barometer balances atmospheric pressure against the pressure exerted by the mercury column.
Correct answer: Atmospheric- A. Depends only upon the open loop transfer function
- B. Determines its stability
- C. All A , B & C.
- D. Is the same for set point or load changes
Explanation: The characteristic equation comes from the denominator of the closed-loop transfer function, and its roots determine stability.
Correct answer: All A , B & C.- A. Impulse
- B. Unit step
- C. None of these
- D. Frequency
Explanation: A sinusoidal input is used to determine a system's frequency response, which describes the steady-state gain and phase at different…
Correct answer: Frequency- A. Elimination of offset
- B. Reduction of offset
- C. Reduction of stability time
- D. None of these
Explanation: Proportional control alone usually leaves a steady-state offset after a load change.
Correct answer: Elimination of offset- A. Roots of the characteristic equation should be real
- B. Poles of the closed loop transfer function should lie in the left half of the complex plane
- C. Bode plots of the corresponding open loop transfer function should monotonically decrease
- D. Poles of the closed loop transfer function should lie in the right half of the complex plane
Explanation: A continuous-time linear feedback system is stable when all closed-loop poles lie in the left half of the s-plane.
Correct answer: Poles of the closed loop transfer function should lie in the left half of the complex plane- A. Insulator
- B. Conductor
- C. Solid semi-conductor
- D. Liquid semi-conductor
Explanation: A thermistor is made from semiconductor materials whose electrical resistance changes strongly with temperature.
Correct answer: Solid semi-conductor- A. Voltage measuring
- B. Temperature measuring
- C. Temperature compensating
- D. Both B. & C.
Explanation: Thermistors are commonly used to measure temperature and to compensate for temperature-dependent changes in circuits.
Correct answer: Both B. & C.- A. Pointer
- B. Bourdon tube
- C. Bulb
- D. None of these
Explanation: The bulb senses temperature and is the primary element, while the Bourdon tube responds to the resulting vapour pressure and acts as the…
Correct answer: Bourdon tube- A. Mercury in glass thermometer
- B. Filled system thermometer
- C. Radiation/infrared pyrometer
- D. Thermo electric pyrometer
Explanation: A radiation or infrared pyrometer detects thermal radiation emitted by the object, so it can measure temperature without physical contact.
Correct answer: Radiation/infrared pyrometer- A. Bright sunshine period
- B. None of these
- C. Diffuse radiation
- D. Beam radiation
Explanation: A pyrheliometer is designed with a narrow field of view to measure direct solar radiation, also called beam or normal-incidence radiation.
Correct answer: Beam radiation- A. Low loads
- B. Temperature changes
- C. Flow rate changes
- D. None of these
Explanation: On-off control is simple but causes cycling around the set point, so it is generally suitable for low-load processes where this variation…
Correct answer: Low loads- A. Pirani
- B. Mcleod
- C. Thermocouple
- D. None of these
Explanation: A pressure of 0.0001 absolute psi is an extremely high vacuum, about 0.005 torr.
Correct answer: Mcleod- A. Chromel-alumel
- B. Iron-constantan
- C. Platinum-platinum + rhodium
- D. Either A., B. or C.
Explanation: A platinum-platinum-rhodium Type S thermocouple produces approximately 5.5 mV at 600°C.
Correct answer: Platinum-platinum + rhodium- A. Nickel
- B. Invar
- C. Chromel
- D. Brass
Explanation: Brass has a linear expansion coefficient of roughly 19 × 10⁻⁶ per °C, higher than nickel and chromel, while invar has an exceptionally low…
Correct answer: Brass- A. Bellows
- B. U-tube
- C. Bourdon tube
- D. Diaphragm
Explanation: Bellows, diaphragms and Bourdon tubes are elastic mechanical elements that deform under pressure.
Correct answer: U-tube- A. Oxygen
- B. Carbon dioxide
- C. Carbon monoxide
- D. Sulphur dioxide
Explanation: A thermal-conductivity cell detects changes in gas composition from the difference in thermal conductivity between the sample and a…
Correct answer: Carbon dioxide- A. Parabolic
- B. Non-linear
- C. Linear
- D. Hyperbolic
Explanation: Over its normal operating range, the difference in expansion of the two bonded metals produces a deflection that is approximately…
Correct answer: Linear- A. 2/s2
- B. 4/s2
- C. 2/s3
- D. 4/s3
Explanation: Using L{tⁿ} = n!/sⁿ, L{2t²} equals 2(2!)/s³ = 4/s³. The power of s increases with the power of time, so 4/s² is the common distractor.
Correct answer: 4/s3