Question

A given length of a wire is doubled on itself.By what factor does the resistance of the wire changes?

Answer 1

resistance is inversily proportional to length

r1 = (Ra)/l          --(1)

where r = resistance, R = restivity , a = area of cross section , l= length of wire

when length get doubled

r2 = (Ra)/2l      -(2)

divide eq. 2 by 1 we get,

r2/r1 = {(Ra)/2l}/ {(Ra)/l}                                    (Ra are constant in both)

r2/r1= l/2l

r2/r1 = 1/2

r2 = r1/2

therefore resistance get reduced by 1/2

Answer 2

Explanation:

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