A piece of wire of resistance 20 ohm is drawn out so that its length is increased to twice its - Science - Electricity

Question

A piece of wire of resistance 20 ohm is drawn out so that its
length is increased to twice its original length Calculate the
resistance of the wire in the new situation?

Ruhhi Ralhan · Accepted Answer

Dear Student,

We know,

$R = ρ \frac{l}{A} = 20 Ω$

Now, if we stretch the same wire in such a way that its length get double. At the same time its area of cross-section decreases to half. So that,

$R' = ρ \frac{l'}{A'} = ρ \frac{2 l}{\frac{A}{2}} = 4 ρ \frac{l}{A} = 4 R = 80 Ω$

A piece of wire of resistance 20 ohm is drawn out so that its length is increased to twice its original length. Calculate the resistance of the wire in the new situation?