$A$ coil carrying a steady current is short-circuited. The current in it decreases $\alpha$ times in $t_0$. The time constant of the circuit is:-

  • A
    $\tau = t_0 \log_e \alpha$
  • B
    $\tau = \frac{t_0}{\log_e \alpha}$
  • C
    $\tau = \frac{t_0}{\alpha}$
  • D
    $\tau = \frac{t_0}{\alpha - 1}$

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