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. (1 - e^-1)
• C. (1 - e)
• D. e

Answer 1

Answer: (B)

(1 - e^-1)

Answer 2

By using $i = i_{0}\left( 1 - e^{- \frac{Rt}{L}} \right)$; $i = \frac{5}{5}\left( 1 - e^{- \frac{5 \times 2}{10}} \right)$

or $i = (1 - e^{- 1})$