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  • If a copper wire is streached to make it  longer, its resisitance will - <s

If a copper wire is streached to make it 0.4% longer, its resisitance will - 

Option: 1

Increased by 0.4%


Option: 2

Increased by 0.8%


Option: 3

Decreased by 0.4%


Option: 4

Decreased by 0.8%


Answers (1)

best_answer

\text { Resistance }(R)=\frac{\rho l}{A} ----(I)

On streaching, volume (V) remains comstant.

So V=AI or A=\frac{V}{I}

Therefore log on bothsides and differentiating

\frac{\Delta R}{R}=\frac{2 \Delta l}{l},(\because V \text { and } \rho \text { are constants) }

\frac{\Delta R}{R} \%=\frac{2 \Delta l}{l} \%

Hence, when the wire is streached by 0.4% its resistance will increased by 0.8%

Posted by

himanshu.meshram

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