Question

A wire is uniformly stretched to make its area of cross-section 1/nᵗʰ times (n > 0). What will be its new resistance (A) 1/n² times
(B) n² times
(C) 1/n times
(D) n times

Answer 1

Dear Student,

◆ Answer -

(B) n² times

● Explanation -

Before stretching, specific resistance of wire is -

ρ = RA/l

Even after stretching, volume of stretched wire will remain same.

V = V'

l.A = l'.A'

l.A = l'.A/n

l' = l.n

Resistance of new wire will be -

R' = ρ.l'/A'

R' = (RA/l) × (l.n) / (A/n)

R' = R.n²

Therefore, new resistance of the wire will n² times of old one.

Hope that's all...