Question

A cylindrical wire is stretched such that its length gets doubled but volume remains same, the resistance of wire becomes :-

• A. four times
• B. remains same
• C. half
• D. becomes double

Answer 1

The correct option is A four times

Resistance $R=\frac{\rho l}{A}=\frac{\rho l^2}{V}$
As volume V remains same so $R\propto l^2$
Thus when length $l$ is doubled, the resistance becomes four times.