Process Control and Instrumentation MCQ Test - Set 01 - ObjectiveBooks

# Practice Test: Question Set - 01

1. When a bare thermocouple is covered by a protective sheath, the response becomes
(A) Faster and oscillatory
(B) Faster and non-oscillatory
(C) Slower and oscillatory
(D) Slower and non-oscillatory

2. Which of the following thermocouples is incapable of measuring sub-zero (i.e., < 0°C) temperature?
(A) Chromel-alumel
(B) Iron-constantan
(C) Platinum-platinum + rhodium
(D) Copper-constantan

3. __________ temperature scale assigns 0° to the 'ice point' and 80° to the 'steam point'.
(A) Celsius
(B) Rankine
(C) Reaumur
(D) Fahrenheit

4. "An emf of the order of mV is generated when two solutions of different hydrogen ion concentration are separated by a thin glass wall". This is the working principle of a
(A) pH meter
(B) Polarimeter
(C) Chromatograph
(D) Polarograph

5. The transfer function of a process is 1/(16s2 + 8s + 4). If a step change is introduced into the system, then the response will be
(A) Under damped
(B) Critically damped
(C) Over damped
(D) None of these

6. A control system has the following transfer function
F(s) = [(s - 1)(s + 1)]/[s (s - 2)(s + 4)]
The initial value of the corresponding time function is
(A) 1
(B) 1/8
(C) 7/8
(D) -1

7. Bode diagram is a plot of
(A) log (ARvs. log (f) and (φ) vs. log (f)
(B) log (ARvsf and log φ vs. f
(C) AR vs. log (f) and φ vs. log (f)
(D) None of these

8. Block diagram of a simple standard control system is shown below in the figure. Which of the following statement about the above control system is wrong?
(A) The transfer functions of the measuring element and the process is represent by H and G2 respectively
(B) The overall transfer function for the change in load (X = 0) is given by Y/X1 = (Gc . G1 . G2)/(1 +  Gc . G1 . G2 . H)
(C) The overall transfer function for the change in set point (X1 = 0) is given by Y/X = (Gc . G1 . G2)/(1 +  Gc . G1 . G2 . H)
(D) Manipulated variable is represented by C

9. A bolometer is
(A) Used for the measurement of thermal radiation
(B) An element which senses optical input and delivers thermal output
(C) Both (a) & (b)
(D) Neither (a) nor (b)

10. The frequency at which maximum amplitude ratio is attained is called the __________ frequency.
(A) Corner
(B) Resonant
(C) Cross-over
(D) Natural

11. The time constant of a first order process with resistance R and capacitance C is
(A) R + C
(B) R - C
(C) RC
(D) 1/RC

12. Thermocouple is suitable for measuring
(A) Liquid temperatures only
(B) Very high temperatures only
(C) Very low temperatures only
(D) Both high and low temperatures

13. Very low pressure is expressed in microns (μ), which is equal to __________ mm of Hg column (absolute) at 0°C.
(A) 0.0001
(B) 0.001
(C) 0.01
(D) 0.1

14. For the time domain function f(t) = t, the Laplace transform of ∫0t f(t) dt is given by
(A) 1/2 S3
(B) 2/S3
(C) 1/S3
(D) 2/S2

15. What is the overall transfer function (C/R) of the following block diagram if G = G1G2G3 and H = H1.H2.
(A) 1/(1 + GH)
(B) G/(1 + GH)
(C) H/(1 + GH)
(D) G/(1 - GH)

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