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2. A metallic wire of specific resistance s is stretched in such a way that its length is doubled

and area of cross section is halved. Then the specific resistance of the wire will be

Answer 1

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Amarnathreddy answered 2 year(s) ago

A wire of length L and R is stretched so that its length is doubled and the area of cross section is halved. How will its (i) Resistance change (ii) Resistivity change.

A wire of length L and R is stretched so that its length’s doubled and the area
of cross section is halved. How will its
(i) Resistance change
(ii) Resistivity change.

Class-X Physics

person

Asked by Apurbo

Jul 2

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Amarnathreddy , SubjectMatterExpert

Member since Jul 09 2013

Data:

Let new length = l'
new Area =, A' and  
new resistance = R'

Given, l' = 2l and A' = A/2 

As we know

R = (ρl) / A

So, R' = [ρ × 2l] / (A/2) = (4 × ρl) / A = 4 × (ρ l / A ) 
but R = ρl/A

⇒  R' = 4 ×R

Resitivity depends on the nature of material not on the length, temperature or Area of cross-section.

So, resitivity will remain Constant.

Answer 2

I hope it helps u ...........................