Assertion : If the length of the conductor is doubled, the drift...

Assertion : If the length of the conductor is doubled, the drift velocity will become half of the original value (keeping potential difference unchanged). Reason : At constant potential difference, drift velocity is inversely proportional to the length of the conductor.

Options

AIf both assertion and reason are true and reason is the correct explanation of assertion.
BIf both assertion and reason are true but reason is not the correct explanation of assertion.
CIf assertion is true but reason is false.
DIf both assertion and reason are false.

Correct answer

A. If both assertion and reason are true and reason is the correct explanation of assertion.

Step-by-step solution

Drift velocity of free electron is given by

v_d=\frac{e E}{m} \tau

Here,

E=\frac{V}{l}

\therefore \quad v_d=\frac{e V}{m l} \tau

v_d \propto \frac{1}{l}\left(\frac{e V}{m} \tau\right.

is constant

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