Process Control and Instrumentation problems
- 1. The transfer function of a second order system is
Options- A.
- B.
- C.
- D. none of these Discuss
Correct Answer:
- 2. Emf generated in a thermocouple depends on the temperature
Options- A. of cold junction only.
- B. of hot junction only.
- C. difference between hot and cold junctions.
- D. difference between cold junction and atmospheric temperature. Discuss
Correct Answer: difference between hot and cold junctions.
- 3. A first order system with a time constant of 1 min is subjected to frequency response analysis. At an input frequency of 1 radian/min, the phase shift is
Options- A. 45°
- B. -90°
- C. -180°
- D. -45° Discuss
Correct Answer: -45°
- 4. A system with a double pole at the origin is unstable since the corresponding term in the time domain
Options- A. is a constant.
- B. grows exponentially with time.
- C. grows linearly with time.
- D. decays linearly with time. Discuss
Correct Answer: grows linearly with time.
- 5. A photo electric device in which the resistance of the metal is directly proportional to the light striking on it, is known as photo-conductive cell. Photoelectric transducers are used for the measurement of those parameters, which can be used to produce variation in
Options- A. light intensity
- B. current
- C. flux density
- D. voltage Discuss
Correct Answer: light intensity
- 6. pH meter has
Options- A. one cell
- B. two cells
- C. three cells
- D. no cell Discuss
Correct Answer: two cells
- 7. Radiation thermometer can not measure the temperature
Options- A. inside a pressure vessel.
- B. of an object without coming in contact with it.
- C. of liquid oxygen.
- D. of moving objects at high temperature. Discuss
Correct Answer: of liquid oxygen.
- 8. Thermal wells are used in the temperature measurement to
Options- A. guard against corrosive and oxidising action on thermocouple materials
- B. reduce measuring lag.
- C. increase the fidelity.
- D. increase the sensitivity. Discuss
Correct Answer: guard against corrosive and oxidising action on thermocouple materials
- 9. Which of the following thermocouples is the most suitable for measuring a temperature of about 1600°C in an oxidizing atmosphere?
Options- A. Platinum-platinum + rhodium
- B. Iron-constantan
- C. Copper-constantan
- D. Chromel-alumel Discuss
Correct Answer: Platinum-platinum + rhodium
- 10. To increase the speed of response of a pressure spring liquid or gas expansion thermometer, the clearance space between the thermometer bulb and the thermal well should not be filled with
Options- A. air
- B. a metal powder or graphite
- C. oil
- D. mercury Discuss
Correct Answer: air
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