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InterviewSolution
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`1kg` piece of copper is drawn into a wire `1mm` thick and another piece into a wire `2mm` thick. Compare the resistance of these wires. |
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Answer» Correct Answer - `16: 1` Let `d` be the meterial of copper wire Let `l_(1) and l_(2)` be length of copper wires of diameter `1mm and 2 mm` respectively. As mass = volume `xx` density `[(piD^(2)//4)xxl]d`, so `1 = (pi (10^(-3))^(2))/(4) l_(1) xx d = (pi( 2xx 10^(-3))^(2))/(4)l_(2) xx d` or `l_(1) = 4 l_(2)` `:. R_(1) = (rhol_(1))/(piD_(1)^(2)//4) = (rho4l_(2))/(pi(10^(-3))^(2)//4)` or `R_(2) = (rhol_(2))/(piD_(2)^(2)//4) = (rhol_(2))/(pi(2 xx 10^(-3))^(2)//4)` so `(R_(1))/(R_(2)) = 16 or R_(1) = 16 R_(2)` |
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