Question

What is the value of the shunt resistance (S) required if a galvanometer has a resistance f 50 Ω and a maximum of 0.05A current that can be passed through it? The ammeter range is changed to 20 A.

(a) 0.120 Ω

(b) 0.125 Ω

(c) 0.130 Ω

(d) 0.145 Ω

This question was posed to me in an interview for job.

I would like to ask this question from Moving Coil Galvanometer in portion Moving Charges and Magnetism of Physics – Class 12

Answer 1

The correct option is (b) 0.125 Ω

Best explanation: Given: Ig = 0.05 A; G = 50 Ω; I = 20 A

Required equation ➔ S = Ig × \(\frac {G}{(I – I_g)}\)

S = \(\frac {0.05 \times 50}{(20 – 0.05)}\)

S = \(\frac {2.5}{19.95}\)

S = 0.125 Ω

Therefore, the required shunt resistance is 0.125 Ω.