Question

In dc tacho generators used for measurement of speed of shaft, frequent calibration is necessary because

a.

contacts wear off

b.

strength of permanent magnet decreases with age

c.

armature current produces heating effect

d.

there is back emf

Answer: (b).strength of permanent magnet decreases with age

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Q. In dc tacho generators used for measurement of speed of shaft, frequent calibration is necessary because

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