Question

If length of given cylindrical wire is increased by 100 % due to concequent decrease in diameter then what will be the percentage change in resistance of wire?

Answer 1

As we know
R = p L/A

New l` = 2l ..

Due to increase in length, area must decrease as volume remains constant..

Al = A`l`

Hence, A` = A/2

New Resistance R` = pl`/A` = 4pl/A
Change in resistance = 3pl/A or 300 %

Answer 2

Answer: 300%

Explanation: See the attached file..