Question

a wire of length l and radius r having resistance 10, radius of wire becomes half when we stretch the wire. find new resistance​

Answer 1

Ans: 40 ohm

Explanation :

R = p l/ A

R is resistance, p is resistivity, l is length and A is Area

Given, R = 10 ohm

r (radius of wire) = half ( r/ 2)

A ( area of wire)= π r^2

Now, A= π ( r/ 2)^2

A = π r^2/4

We know that,

Resistance is inversely proportional to Area

Therefore, Resistance becomes 4 times

R = ( 4× 10 ) ohm

New Resistance is 40 ohm