A moving coil galvanometer has a resistance of 40 Ω. It gives a full scale deflection with a current of 2 mA. How is to be modified to convert it to a voltmeter of 5 V range by connecting some resistance?

2460 Ω connected in series with galvanometer

The correct answer is Option (2) → 2460 Ω connected in series with galvanometer

To convert the moving coil galvanometer into a voltmeter of a given range, one need to connect a series resistance known as resistance multiplier.

Desired voltage range, $V=I_f×R_{total}$

$⇒R_{total}=\frac{V}{I_f}=\frac{5}{0.002}=2500Ω$

$R_{total}=R_G+R_S$  [$R_G$ = Resistance of galvanometer]

$2500=R_S+40$

$⇒R_S=2460Ω$