Question

Wire of a certain material is stretched slowly be dep10. Its new resistance and specific resistance becomes respectively.

• A. Both remain same
• B. 1.1 times in both
• C. 1.2 times , 1.1 times
• D. 1.21 times, same

Answer 1

Answer: (D)

1.21 times, same

Resistance of the wire $R=\frac{\rho l^2}{V}$

Length of the wire after it is stretched $l^{\prime }=1.1l$

$\therefore$ New resistance $R^{\prime }=\frac{\rho (1.1l{)}^2}{V}=1.21R$

Specific resistance is an intrinsic property of a material and it does not depend on the dimension of the conductor. Hence specific resistance remains the same even when the wire is stretched.