How is a moving coil Galvanometer converted into Voltmeter? Explain giving the necessary circuit diagram and the required mathematical relation used.

A galvanomter can be converted into voltmeter by connected a high resistance in series with the galvanometer. 



Let G = resistance of galvanometer

n = number of scale divisions in the galvanometer

K = figure of merit of galvanometer

Current which produce full deflection in the galvanometer, Ig = nK
 
Let V be the potential difference to be measured by galvanometer.

 If R be the resistance connected in series. Then

Total resistance of galvanometer = R + G

From ohm's law
Ig=VR+GR+G=V IgR=VIg-G


 

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