A coil having inductance 2.0 H and resistance `20 Omega` is connected to a battery of emf 4.0 V. Find (a) the current a the instant 0.20 s after the connection Is made and (b) the magnetic energy at this instant.

Answer

A, B, C

Explanation

(a)`I=I_(0)(1-e^(-t//tau))`
where `i_(0)=4/20=1/5`
`tau=L/R=2/20=1/10`
and `t=0.2 sec`
(b)`E=1/2L I^(2)`