A conducting wire of length 'l', area of cross-section A and electric… | JEE Main 2021 (16 Mar, Shift 1)

Q23JEE Main 2021 · 16 MAR · SHIFT 1Medium

Electric Current, Drift Velocity & Current Density

A conducting wire of length 'l', area of cross-section A and electric resistivity $\rho$ is connected between the terminals of a battery. A potential difference V is developed between its ends, causing an electric current.

If the length of the wire of the same material is doubled and the area of cross-section is halved, the resultant current would be:

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Answer: (c)

Initially $R = \dfrac{\rho l}{A}$
New $R' = \dfrac{\rho (2l)}{A/2} = \dfrac{4\rho l}{A}$
$I' = \dfrac{V}{R'} = \dfrac{1}{4}\dfrac{VA}{\rho l}$
So the answer is (c).

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Electric Current, Drift Velocity & Current Density question from JEE Main 2021 (16 Mar, Shift 1)

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