Question

What is the effect on null deflection of galvanometer, when the radius of the wire is tripled?

(a) No change

(b) Becomes half

(c) Reduces by \(\frac {1}{3}\)

(d) Thrice the original value

I have been asked this question in exam.

I'd like to ask this question from Current Electricity in division Current Electricity of Physics – Class 12

Answer 1

Right answer is (a) No change

Best explanation: For a balanced Meter Bridge \(\frac {P}{Q} = \frac {x}{(100-x)}\). From this, we can understand that the null deflection of galvanometer does not depend on the radius of the wire. So, even if the radius of the wire is tripled, the null deflection of the galvanometer undergoes no change.