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The resistance of wire is 10 Omega IF th...

The resistance of wire is `10 Omega` IF the length of wire is increase by n% the new resistance is `10.2 Omega` then n…..

A

1

B

2

C

3

D

4

Text Solution

Verified by Experts

The correct Answer is:
A
Here `l_2=l_1+(n% of l_1)`
`=l_1+(l_1 times n/100)`
`therefore l_2=l_1(1+ n/100)`
When a wire is stretched uniformly, its electrical resistance
`R propl^2`
`therefore R_1/R_2=l_1^2/l_2^2`
`therefore R_1/R_2=l_1^2/(l_1^2(1+n/100)^2)`
`therefore R_1/R_2=1/(1+n/100)^2`
`therefore 10/10.2=1/(1+n/100)^2`
`therefore(1+n/100)^2=10.2/10=1.02`
`therefore 1+n/100=sqrt1.02=1.00995`
`therefore n/100=0.00995`
`therefore n=0.995 =1`
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