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A piece of wire of resistance 10 ohm is ...

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.

Text Solution

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Specific resistance `(rho)=(RA)/(l)`
`R=(rhol)/(A)`
When the length is increased by three and then the area of cross section is reduced by three
Resistance of wire `R=10Omega`
New resistance `R.=(rho(3l))/((A//3))`
`=rho(3l)xx(3)/(A)`
`=(9rhol)/(A)`
`=9xxR`
`=9xx10`
`R.=90Omega`
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