Question

An ideal coil of 10 henry is joined in series with a resistance of 5 ohm and a battery of 5 volt. 2 second after joining, the current flowing in ampere in the circuit will be

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

Answer 1

Answer: (B)

$\left( 1 - e ^ { - 1 } \right)$

Answer 2

From$i = i _ { 0 } \left[ 1 - e ^ { - R t / L } \right]$, where $i _ { 0 } = \frac { 5 } { 5 } = 1 \mathrm { amp }$

$\therefore i = 1 \left( 1 - e ^ { \frac { - 5 \times 2 } { 10 } } \right) = \left( 1 - e ^ { - 1 } \right) a m p$