Question

An ideal coil of $10\, H$ is joined in series with a resistance of $5 \,\Omega$ and battery of $5\, V,\, 2 s$ after joining the current flowing (in ampere) in the circuit will be

• A. $ {{e}^{-1}} $
• B. $ (1-{{e}^{-1}}) $
• C. $ (1-e) $
• D. $e$

Answer 1

Answer: (B)

Given, $L=10\, H,\, R=5 \Omega,\, E=5\, V$
and $t=2\, s$.
Current in $R-L$ circuit
$I=I_{0}\left(1-e^{-R t / L}\right)$
$I=\frac{E}{R}\left(1-e^{-R t / L}\right)$
$=\frac{5}{5}\left(1-e^{-5 \times 2 / 10}\right)$
$I=\left(1-e^{-1}\right)$