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When a voltage measuring device is conne...

When a voltage measuring device is connected to AC mains, the meter shows the steady input voltage of 220V. This means

A

input voltage cannot be AC voltage, but a DC voltage.

B

maximum input voltage is 220V.

C

the meter reads not v but `lt v^2 gt` and is calibrated to read `sqrt(ltV^2gt)`

D

the pointer of the meter is stuck by some mechanical defect.

Text Solution

Verified by Experts

The correct Answer is:
C
AC voltmeter reads the rms value of voltage,
`therefore V_"rms"=V_m/sqrt2`
The voltmeter connected to AC mains read mean value `ltV^2gt` (average value) and is calibrated in such a way that it gives value of `ltV^2gt`. This is obtained by dividing `sqrt2` to maximum voltage `V_m`.
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