Question

a wire of length L and resistance R is stretched so that its length is doubled and the area of cross-section is halved.how will it's 1) resistance change 2)resistivity change.pls answer fast urgentttt

Answer 1

check the solution sent.

Answer 2

(a) The new resistance becomes 4 times of the initial resistance.

(b) Resistivity remains the same.

Explanation:

The resistance of a wire of length L and resistance R is given by :

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

If a wire of length L and resistance R is stretched so that its length is doubled and the area of cross-section is halved. It means, L' = 2L and A' = A/2. New resistance becomes :

$R'=\rho \dfrac{L'}{A'}\\\\R'=\rho \dfrac{(2L)}{(A/2)}\\\\R'=4\times \rho \dfrac{L}{A}\\\\R'=4R$

So, the new resistance becomes 4 times of the initial resistance.

(2) The resistivity of a wire remains the same on changing its length and area of cross section.

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