Question

An inductor $(L=100mH)$, a resistor $(R=100\Omega )$ and a battery $(E=100V)$ are initially connected in series shown in the figure. After a long time the battery is disconnected after short circuiting the points A and B. The current in the circuit, $1ms$ after the short circuit is:

• A. $1/eA$
• B. $eA$
• C. $0.1A$
• D. $1A$

Answer 1

The correct option is A $1/eA$

current after short circuiting is discharging of inductor
$i=\left(\frac{E}{R}\right)e^{\frac{-tR}{L}}$
$t=0.001$
$=\frac{100}{100}\exp \left(\frac{-.001\times 100}{{10}^{-3}\times 100}\right)$
$=e^{-1}A$