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  • Solve! A copper wire is stretched to make it 0.1 % longer. The percentage change in its resistance is

A copper wire is stretched to make it  0.1 % longer.  The percentage change in its resistance is

  • Option 1)

    0.2 % increase

  • Option 2)

    0.2% decrease

  • Option 3)

    0.1 % increase

  • Option 4)

    0.1 % decrease

 

Answers (1)

best_answer

As we learnt

 

Ratio of resistances -

 

If length is given

R \alpha l^{2}

- wherein

\frac{R_{1}}{R_{2}}=\left (\frac{l_{1}}{l_{2}} \right )^{2}

 

 

  For a given wire, R = \frac{{\rho L}}{s}$
with  L ´ s = volume  = V = constant
so that R = r \frac{{{L^2}}}{V}$
\frac{{\Delta R}}{R}$ = 2 \frac{{\Delta L}}{L}$ = 2 (0.1 %)  
= 0.2 % (increase)

 


Option 1)

0.2 % increase

Option 2)

0.2% decrease

Option 3)

0.1 % increase

Option 4)

0.1 % decrease

Posted by

Aadil

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