Question

The wire of lenth L and resistance R is stretched so that its radius of cross section is halved what is its new resistance

Answer 1

$\huge\color{red}{A.T.Q}$

:- 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.✔✔

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