Question

A wire of resistivity 2 is strectched to double its length. What will be the new resistivity now?

Answer 1

R is proportional to l^2. Then, if we double l, R becomes R'=4R. When the wire is stretched to double the length , the area of cross section gets reduced to half. So when the wire is stretched, the resistance multiplies by four times

Answer 2

Answer:

p' = 4p

Explanation:

As the wire is strecthed to double the length rhen its area will be reduced to hakf i.e R/2

so now

Resistivity p = L / RA

so new resistivity ,

p' = L' / RA'

= 2L / R (A/2)

= 4 (L/RA)

=4 p (answer)