Question

If the length of a wire is doubled by stretching it what will be the change in its resistance and resistivity?

Answer 1

Answer:

Resistance becomes 4 times and resistivity remains same.

Explanation:

When, a wire is stretched, it's volume remains constant. So, product of Area and length is constant i.e.,

$l*A = const.$

So, with this relation, when length is doubled, the area becomes half.

Also, the resistivity of a wire is constant at a fixed temperature. So, resistivity (ρ) doesn't change here.

Now,

R = ρ * $\frac{l}{A}$

Hence, the Resistance (R) becomes 4 times the initial value.