Question

${\bold{\red{Question:}}}$

A piece of wire of resistance 20 ohm is drawn out so that it's length is increased to twice it's original length . calculate the resistance of the wire in the new situation.
${\bold{\Green{Solve\:This\: Numerical\: Problem}}}$

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Answer 1

${\bold{\red{✍Solution :}}}$

When length of wire is doubled i.e. 2l (say)

Area of cross section becomes half i.e A/2Resistance R = ρl/A= 20

R' = ρl/A

R' = ρl/A=ρ(2l)*2/A

R' = ρl/A=ρ(2l)*2/A=4ρl/A= 4(pl/A)

= 4*20= 80ohm✔︎

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Answer 2

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