Process Control and Instrumentation

81. For increased speed of response of an expansion pressure spring thermometer, the thermometer bulb should have a

1. Large area but small mass
2. High thermal conductivity
3. Small specific heat
4. All 'a', 'b' & 'c'

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82. For measuring the temperature of a red hot furnace, which is the most suitable instrument?

1. Platinum resistance thermometer
2. Thermocouple
3. Optical pyrometer
4. Bimetallic thermometer

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83. For the block diagram shown below: The characteristic equation is

1. ηl S (ηps + 1) + K_c . Kp (ηlS + 1) e-η d s = 0
2. (ηmS + 1) (ηpS + 1) + Km . Kp e-η d S = 0
3. ηl S(ηm S + 1) (ηp S + 1) +K_c . Kp . Km (ηl s + 1) e-τdS = 0
4. (ηms + 1) (ηp s + 1) + K_c . Kp . Km . e-η d S = 0

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84. For the time domain function f(t) = t, the Laplace transform of ∫0 t f(t) dt is given by

1. 1/2 S³
2. 2/S³
3. 1/S³
4. 2/S²

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85. For two non-interacting first order systems connected in series, the overall transfer function is the _________ of the individual transfer functions.

1. Product
2. Ratio
3. Sum
4. Difference

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86. Gain margin is equal to the

1. Amplitude ratio
2. Reciprocal of amplitude ratio
3. Gain in P controller
4. Gain in P-I controller

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87. Gas analysis is commonly done using the

1. Thermal conductivity cell
2. X-ray diffraction
3. Mass spectrometer
4. Emission spectrometer

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88. Gas chromatography is used for the measurement of

1. Temperature
2. Pressure
3. Concentration
4. Flow rate

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89. Helium gas constant volume thermometer is suitable for the measurement of a temperature of _________ °C.

1. < 100
2. < 0
3. < 0
4. < 800

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90. High temperature of around 2000°C of incandescent gas mantles is measured by a/an

1. Specially designed thermocouple
2. Optical pyrometer
3. Radiation pyrometer
4. None of these

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