When length of wire is increased by 10% , then increase in resistance is
When length of wire is increased by 10% , then increase in resistance is
A. 0.1
B. 0.21
C. 0.25
D. 0.35
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Correct Answer - B
`l_(2)=1.1 l_(1), R_(2)-R_(1)=?`
`(R_(2))/(R_(1))=((l_(2))/(l_(1)))^(2)`
`R_(2)=((1.1 l_(1))/(l_(1)))^(2)xxR_(1)=1.21 R_(1)`
Now increase in resistance `= R_(2)-R_(1)` and
% increase in resistance `= ((R_(2)-R_(1))/(R_(1)))xx100`
`=((1.21R_(1)-R_(1))/(R_(1)))xx100`
`=21%`
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