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zxcv

The resistvity of iron metal is 1*10^-7ohm metre.The resistance of iron wire at a particular length and thickness is 1ohm. If the length and diametre of wire both are doubled, then the resistivity in ohm metre will be?

iitkgp_bipin

Resistivity is constant for a metal for a constant temperature.
So, when the length and diameter are changed there is no change in resistivity.

However its resistance will change.
Since resistance is proportional to length/area its value would be halved.

waterdemon

The resistivity will become half of that of the original .

Resistivity = Length / Area of cross section

Here

Length is doubled , Thickness is doubled

l = 2L . R=2r

So

Resistivity = 2L /

( 2r)²

Resistivity = 1/2 * L /

r²

Hence resistivity = 5 * 10^-8

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bhuvana89

resistivity will not change since its is characteristic property of a material.
however it will change with chanGes in TEMPERATURE AND PRESSURE.
I don't know how it changes with pressure , but it is mentioned in ncert.if nyone has ny information plz reply.

elessar_iitkgp

Bipin is absolutely correct.
Resistivity of a conductor is its characteristic property that changes only with change in temperature. As certain changes in pressure may be accompanied by changes in temperature as well, it can be said to be dependent on pressure as well.

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