Process Control and Instrumentation

171. Routh test

1. Criterion provides information about the actual location of roots
2. Cannot be used to test the stability of a control system containing transportation lag
3. Criterion is not applicable to systems with polynomial characteristic equation
4. Cannot determine as to how many roots of the characteristics equation have positive real roots

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172. Select the correct statement from the following.

1. The frequency response of a pure capacity process is unbounded
2. The phase lag of a pure time delay system decreases with increasing frequency
3. The amplitude ratio of a pure capacity process is inversely proportional to frequency
4. The amplitude ratio of a pure time delay system increases with frequency

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173. Silver point temperature is _________ °C.

1. 760.5
2. 860.5
3. 960.5
4. 1060.5

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174. Small furnace draught is accurately measured by an inclined tube manometer, in which the manometric liquid used most commonly is

1. Water
2. Carbon tetrachloride
3. Paraffin
4. Ethylene glycol

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175. Smoke density of the flue gas going out of the chimney is measured by a

1. Polarograph
2. Thermal conductivity meter
3. Photo electric cell
4. Chromatograph

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176. Specific conductance is defined as the reciprocal of resistance in ohms of 1c.c. of liquid at a specified temperature. Its value for distilled water is about _________ micro mho/cm3.

1. 50
2. 100
3. 10
4. 1

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177. Specific gravity of a liquid cannot be measured by a/an

1. Anemometer
2. Specific gravity bottle
3. Pycnometer
4. Hydrometer

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178. Stabilising time for the controllers is the time required for the response to reach _________ percent of its ultimate value.

1. 63.2
2. 87.5
3. 95
4. 100

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179. Stability of a control system containing a transportation lag can be best analysed by

1. Routh test
2. Root locus methods
3. Frequency response methods
4. None of these

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180. Stalagmometer is used for the measurement of

1. Kinematic viscosity
2. Surface tension
3. Refractive index
4. Optical activity

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