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A resistive wire is stretched till its length is increased by 100%. Due to the consequent decrease in diameter, the change in the resistance of a stretched wire will be |
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Answer» 3 LET length of wire is l and area is A. R = `(rho l)/(A)` New length of wire l. = l + 100% l = 21 and area is A.. `THEREFORE (R.)/(R) = (rho l. )/(A.) (A)/(rho1)= (A)/(A.) (l.)/(l) = ((l.)/(l) )^(2)= ((2l.)/(l) )^(2) = 4` `R. = (rho l.)/(A.)` `therefore R. = 4R = R + 3R = ((4R - R)/(R) XX 100 ) % ` `= ((3R)/(R) xx 100 )%` = 300 % Percentage change in resistance = 300% |
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