A wire of length L is uniformly stretched to triple its original length.By what factor does its resistance change?
A)1,i.e. ,no change
B)3
C)9

Question

A wire of length L is uniformly stretched to triple its original length.By what factor does its resistance change?
A)1,i.e. ,no change 
B)3 
C)9

Quizplus · Accepted Answer

The resistance of a wire is directly proportional to its length and inversely proportional to its cross-sectional area. As the wire is stretched to triple its original length, its cross-sectional area will decrease to 1/3 of its original area. Thus, the overall resistance will increase by a factor of 9 (3^2). Therefore, the correct answer is the choice letter C.

A Wire of Length L Is Uniformly Stretched to Triple