1.

A piece of wire of resistance 10 ohm is drawn out so that its length is increased to three times its original length. Calculate the new resistance.

Answer»

Resistance R = 10 Ω 

Let l be the length of the wire R ∝ 1 

When the length is increased to three times, 

l’ = 3l 

∴ New Resistance

R’ ∝ l’ ∝ 3l

∴ \(\frac{R}{R'} = \frac{l}{3l} = \frac{1}{3}\)

∴ R' = 3R

New resistance = 3 times the original resistance.



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