Question

If the length of a wire is doubled by taking more of wire, what happens to its resistance?

Answer 1

We know that the resistance of the wire, R = ρl / A where the resistivity of the wire is ρ.

The length of the wire = l
The area of cross-section of the wire, A = πr²

So when the length of the wire is doubled (l' = 2l) by taking more of the same wire, (it will keep the resistivity and the area of cross-section the same), the length is doubled.

New resistance = R'

R' = ρl' / A

R' = 2ρl / A

R' = 2R