The scale of a galvanometer of resistance 100 Ω contains 25 divisions. It gives a deflection of one division on passing a current of 4 × 10-4 A. The resistance (in ohm) to be added to it, so that it may become a voltmeter of range 2.5 V is:
Answer & explanation
Correct answer: option 1
Maximum current possible in galvanometer = 25 × 4 × 10-4 A = 10-2 A
So, $10^{-2}=\frac{25}{100+R}$
100 + R = 250
Resistance, R = 150 Ω