The current i flows in a wire of circular cross-section with the free electrons travelling with a drift velocity v. What is the drift velocity of electrons when a current of 2 i flows in another wire of twice the radius and of the same material ?
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The drift velocity is given by, `v_(d) = i/(nAe) = v` When radius becomes twice, area A becomes four times. As material is same, so n is same. `v_(d)' = (2 i)/(n (4A)e) = 1/2 [(i)/(nAe)] = v/2`
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