Q148 / 160 · AP EAMCET 2015 · Physics

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

  • A
    increases $4$ times
  • Correct answer
    B
    decreases $4$ times
  • C
    increases $2$ times
  • D
    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

Hence, the correct answer is option: 'B'.

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