Question

A copper wire of resistance 4 ohm is stretched to thrice its original length find the resistance of the stretched wire

Answer 1

Given:

The resistance of the copper wire R= 4 ohm

The original length l

The stretched length 3l

To find:

The resistance of the original one.

Solution:

The Resistance is directly proportional to the length.

R'=ρl²/V

R=ρ(3l)²/V

Taking the ration of both the terms.

R/R'= 9l²/l²

R=9R'

As the R'=4

Put back in above equation

R=9×4

R=36 ohm

So the resistance of stretched wire is 36 ohm