Question

Wire of resistivity rho is pulled to double its length what will be the new resistivity

Answer 1

Ïwill be 4 times of initial value

Answer 2

Wire of resistivity rho is pulled to double. its length what will be the new resistivity?

Volume of the material of wire remains same. So, when length is doubled its area of cross-section will get halfed.

So, if l & a are the original length & area of cross-section of the wire,

0riginal value of Resistance,

R = p × l / a

New value of Resistance,

R' = p × 2l / a/2

  = p l/a × 4

  = 4R ...