Question

The resistance of the wire 20 ohm. What will be new resistance ,if it is stretched uniformly 8 times it's original length?

Answer 1

Answer:

pls see the attachment

Answer 2

The new resistance of the wire is 160 ohms.

Explanation:

The resistance of the wire is given by :

$R=\rho\dfrac{l}{A}$

Here, R = 20 ohms

If it is stretched uniformly 8 times, new length is, l' = 8l. New resistance becomes :

$R'=\rho\dfrac{l'}{A}\\\\R'=\rho\dfrac{8l}{A}\\\\R'=8\rho\dfrac{l}{A}\\\\R'=8R$

$R'=8\times 20\\\\R'=160\ \Omega$

So, the new resistance of the wire is 160 ohms.

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