Question

The resistance of certain length wire is R ohm .it is dou
bled on itself so that it's length is half it's new resistance

Answer 1

Answer:

sorry the pic is not so clear may be it will help u

Answer 2

Answer:

R = pl/A

if length become l/2

Al = A'l/2

A' = 2A

then the area of cross section become twice i.e. 2A

R' = pl'/A'

R' = pl/2 / 2A

R' = pl/4A

R' = R/4

thus the new resistance is 1/4th of initial resistance..