MCQ
In an a.c. generator the speed at which the coil rotates is doubled. How would this affect the frequency of output voltage?
- Afrequency is doubled
- Bfrequency is halved
- Cfrequency remains same
- Dcant say
✓
Answer
- frequency is doubled
Explanation:
AC generators are made up of one or more magnetic pole pairs corresponding to their purposes.
The frequency of an AC generator is dependent on the number of pairs of poles and the speed of the coil rotation. The frequency of the induced AC current depends on therevolution
of the coil since, rate of revolution is Revolutions Per Minute (RPM) and frequency is expressed as cycles per second, the frequency of the induced AC current will be the rate of
revolution of the coil divided by 60 seconds.
That is, F = RPM × number of pole pairs ÷ 60
When the Revolutions per minute (RPM) is doubled, then, obviously the frequency of the ac current will also be doubled as the RPM is multiplied with the number of pole pairs.
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