4.27 A galvanometer coil has a resistance of 12 Ω 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?
Resistance of the galvanometer coil, G = 12
Current for which there is full scale deflection,
Range of the voltmeter is 0, which needs to be converted to 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 5988 is to be connected in series with the galvanometer.
