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Two wires `A` and `B` of same material and same mass have radius `2r` and `r`. If resistance of wire `A` is `34 Omega`, then resistance of `B` will beA. 544 `Omega`B. 372 `Omega`C. 68 `Omega`D. 17 `Omega` |
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Answer» Correct Answer - A `R=rho l/A` and mass m = volume (V) x density (d) = (Al)d Since wires have same material so `rho` and d is same for both. Also they have same mass `rArr` Al = constant `rArr l prop 1/A` `rArr R_1/R_2 = l_1/l_2 xxA_2/A_1 =(A_2/A_1)^2=(r_2/r_1)^4` `rArr 34/R^2 = (r/"2r")^4 R_2= 544 Omega` |
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