Question

A galvanometer, whose resistance is $50$ ohm, has $25$ divisions in it. When a current of $4\times 10^{-4}A$ passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range $2.5V$, it should be connected to a resistance of (in ohm)

Answer 1

Answer: 200

Galvanometer has 25 divisions
$I_g=4\times 10^{-4}\times 25=10^{-2}A$

$v=I_g(G+R)$
$2.5=(50+R)10^{-2}$
$\therefore R=200\Omega$