Question

a wire of resistance R is melted and recast into half of its original length the new resistance will be​

Answer 1

Explanation:

initial length L and area A having resistance R

R proportional to L/A

it is recast into half of its length that is L/2,

volume remain same

Lx A = L/2 x A1

A1 = 2A

R( new) proportional to ( L/2)x 1/A1

proportional to (L/2) x 1/ 2A

to 1/4 (L/A)

to 1/4 R