Question

The length of a given cylindrical wire is increased by 100%. Due to consequent decrease in diameter, the change in resistance of wire will be :-

a. 100% b. 200%
c. 50% d. 300%

Answer 1

Answer:

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 %

D) is the answer

THanks

Answer 2

Answer:

The answer of this question is(d).