64. The advantage of wavelength standard is that it would be possible to repeat measurements to a very high degree of accuracy. The wavelength standards can be reproduced to an accuracy of about one part in
A.1000
B.109
C.107
D.108

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65. The basic unit in angular measurements is
A.Degree
B.Minute
C.Second
D.Right angle

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66. Optical gauge works on the principle of
A.Refraction
B.Interference of light rays.
C.Dispersion
D.Polarisation

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67. The micrometer shown in Fig. 6 is called
A.Tube micrometer
B.Depth micrometer.
C.Height micrometer
D.Disc type micrometer

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68. Millimeter scale in a micrometer is marked on
A.Barrel
B.Thimble
C.Spindle
D.Anvil

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69. Circular scale of the micrometer is marked on
A.Anvil
B.Barrel
C.Ratchet
D.Thimble

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70. According to well accepted practice, slip gauges which have been handled for a few minutes should be left for sometime. The reason for this could be
A.The moisture transferred from hand would evaporate
B.The structure of gauges, if disturbed would stabilise
C.Gauges attain the room temperature again
D.(c1) with continuous use, gauges may wear quickly

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