Instrumentation Multiple Choice Questions Answers

61. Which one of the following is the best method of measurement of temperature of hot bodies radiating energy in visible spectrum ?

(a) Thermocouple.
(b) Thermopile.
(c) Optical pyrometer.
(d) Bolometer.

62. Which one of the following is used to measure temperature inside a boiler furnace ?

(a) Resistance thermometer.
(b) Bimetallic thermometer.
(c) Optical pyrometer.
(d) Thermistor.

63. Which is the most suitable thermocouple transducer for the measurement of temperature in the range of 1,300°C to 1,500°C ?

(a) Chromel-alumel.
(b) Platinum-rhodium.
(c) Iron-constantan.
(d) Chromel-constantan.

64. Hot-wire anemometers are used for measuring

(a) gas velocities.
(b) pressure of fluids.
(c) liquid discharges.
(d) very low pressures.

65. The device used for measuring flow of air around an airplane is

(a) rotameter.
(b) venturi meter.
(c) anemometer.
(d) none of these.

66. Consider the following statements:

1. Electromagnetic flowmeter is independent of liquid density.
2. Electromagnetic flowmeter cannot be employed for measuring flow of non-conducting fluids.

Which of the above statements is/are correct?
(a) 1 only.
(b) Both 1 and 2.
(c) 2 only.
(d) Neither 1 nor 2.

67. Which one of the following transducers cannot measure flow in non-conducting medium ?

(a) Orifice meter.
(b) Electromagnetic flow-meter.
(c) Turbine meter.
(d) Rotameter.

68. A flow-meter that is independent of liquid density is

(a) rotameter.
(b) Electromagnetic flow-meter.
(c) venturimeter.
(d) orifice meter.

69. Which of the following transducers is used for transmitting as well as receiving the acoustic energy in an ultrasonic flow-meter ?

(a) LVDT.
(b) RTD.
(c) Piezoelectric crystals.
(d) Strain gauge.

70. Consider the following statements :

1. Ultrasonic technique cannot be used for measurement of flow of a liquid having air bubbles in it.
2. Attenuation of ultrasonic signal is less in air compared to that in a liquid.

Of these statements
(a) 2 is false and 1 is true.
(b) 1 and 2 are true.
(c) 2 is true and 1 is false.
(d) 1 and 2 are false.

71. The main drawbacks of ultrasonic flow-meter are

(a) low accuracy and slow response.
(b) complexity and relatively high cost.
(c) affected by pressure and temperature variations.
(d) none of the above.

72. In radioactive method the receiver measures fluid level by recording the

(a) direction of the rays.
(b) number of radioactive particles received.
(c) time taken by the rays in reaching the receiver.
(d) none of the above.

73. The method; that can be employed for measuring only fluid level, is

(a) radioactive method.
(b) bellows.
(c) strain gauge.
(d) bourdon tube.
(c) bell type meter.

74. Hydrometer is employed for determination of

(a) relative humidity.
(b) specific gravity of liquids.
(c) fluid level.
(d) none of the above.

75. Inductive method can be used for measuring thickness of

(a) magnetic but non-conducting materials.
(b) conducting but non-magnetic materials.
(c) conducting and magnetic materials.
(d) non-conducting and non-magnetic materials.
(e) both magnetic and non-magnetic materials, as well as non-conducting and conducting materials.

76. The non-contact method of measuring thickness or density of cold or hot materials while in motion or when stationary is

(a) inductive.
(b) capacitive.
(c) nuclear radiation.
(d) ultrasonic.

77. The most suitable transducer for monitoring continuously variations in very fine thickness (say of paper in paper industry) is

(a) inductive.
(b) capacitive.
(c) ultrasonic.
(d) nuclear radiation.

78. In hygrometers the principle of measurement is

(a) change in resistance of salts with humidity.
(b) change in microwave power using klystron.
(c) change in thermal conductivity using thermistor.
(d) none of the above.

79. The electrical transducers used for continuous recording and control of humidity are

(a) resistive hygrometers.
(b) electrolytic hygrometers.
(c) aluminum oxide hygrometers.
(d) all of the above.

80. Measurements of flow, thermal conductivity and liquid level using thermistors make use of

(a) resistance decrease with temperature.
(b) resistance increase with temperature.
(c) self-heating phenomenon.
(d) change of resistivity.