Question

10th cbse science book pg no 209
Ex 12.6 i want clear answer

Answer 1

We have given that R=4ohms

When a wire is doubled on it it becomes halved and area of cross section becomes doubled . That is a wire of length is L and area of cross section is A so length become L/2 and area of cross section is 2A

Then R=rho×L/2 /2A

Where R is resistance

Then rho×l/A = 1/4, R = 4ohms/4 so

1ohms

The new resistance of wire willbe 1ohms