A coil of self-inductance `50` henry is joined to the terminals of a battery of e.m.f. `2` volts through a resistance of `10ohm` and a steady current is flowing through the circuit. If the battery is now disconnected, the time in which the current will decay to `1//e` of its steady value is

Options

A. `500` seconds
B. `50` seconds
C. `5` seconds
D. `0.5` seconds

Answer

C

Explanation

Time in which the current will decay to `(1)/(e)` of its
steady value is `t=tau=(L)/(R)=(50)/(10)=5` seconds