Question

find new resistance of a wire if it is stretched to twice its original length original resistance was 20 ohm also how it resistivity will change

Answer 1

hi.......................

Answer 2

let the length of the wire be l,
Than by stretching length = 2l

And let the area be a,
Than by stretching area = a/2

Original Resistivity = R*a / l ( R = Resistance)
= 20a/l

So Resistivity = 20a/l ohmic m

New Resistance = R x l / a ( R = Resistivity)
= 20a / l x 2l / a
= (20x4)a/a
= 80 ohm

New Resistivity = Rxa / l
= 80xa/2 / 2l
= 40a/2l
= 20a/l ohmic m

Hence new Resistivity is also 20a/l because Resistivity is always constant

Hope it helps u

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