CGPET 2012 Solved Paper

As we know that when an L−R circuit is connected to the battery of emf ε, the current at any time, t is given by
i=‌

ε

R

(1−e−tR∕L)=‌

ε

R

(1−e−t∕T)
Here, T= Time constant
R= Resistance of the circuit
and L= Inductance of the inductor used in
the circuit