1)

The resistance of a wire is 'R' ohm. If it is melted and stretched to 'n' times its original length. its new resistance will be


A) Rn

B) n2R

C) Rn2

D) nR

Answer:

Option B

Explanation:

we know that, R = ρlA

or R = ρl2Volume → Rl2

According to question l2=nl1

R2R1=n2l21l21

or R2R1=n2

R2=n2R1