NEET-XII-Physics
04: Moving Charges And Magnetism
- #27A galvanometer coil has a resistance of 12 ``\Omega`` and the metre shows full scale deflection for a current of 3 mA. How will you convert the metre into a voltmeter of range 0 to 18 V?
Ans : Resistance of the galvanometer coil, G = 12 ``\Omega``
Current for which there is full scale deflection,
= 3 mA = 3 × 10-3 A
Range of the voltmeter is 0, which needs to be converted to 18 V.
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V = 18 V
Let a resistor of resistance R be connected in series with the galvanometer to convert it into a voltmeter. This resistance is given as:
Hence, a resistor of resistance
is to be connected in series with the galvanometer.