Question

a copper wire is stretched to make it 0.2 %longer . what is the percentage change in its resistance

Answer 1

ANS : 0.4%

*EXPLANATION*

Whenever a resistance wire is stretched then its volume is unchanged and hence the

resistance equal to (rho × L÷A)

therefore R is equal to (rho × L ÷V ) L

           = (rho×L^2 )V

rho and V are constants

and hence the R  proportional to square  of L

and then (Delta R /R)=( 2 x of delta L÷L) therefore

 DOUBLE OF THE change of the percentage of the length of the resistance wire is equal to change of the percentage of the resistance

means the 0.2% change in this question for the length of a substance wire and hence the electrical resistance changed as double of the 0. 2 =   0.4%    .

SO ANSWER  0.4%

Answer 2

Answer:

Ans: 0.4%

Explanation: Hope its clear.