A constant potential difference is applied between the ends of the wire. If the length of the wire is…

A constant potential difference is applied between the ends of the wire. If the length of the wire is elongated 4 times, then the drift velocity of electrons will be
  1. increases $4$ times
  2. decreases $4$ times
  3. increases $2$ times
  4. decreases $2$ times

Solution

$v_d \propto \frac{1}{l} \frac{v_{d_1}}{v_{d_2}}=\frac{I_1}{I_2}=\frac{4 I}{I} \Rightarrow v_{d_2}=\frac{v_{d_1}}{4}$ So drift velocity will decrease by 4 times

Asked in: AP EAMCET 2015

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