A coil has an inductance of `2.5 H` and a resistance of `0.5Omega`. If the coil is suddenly connected across a `6.0` volt battery, then the time required for the current to rise `0.63` of its final value is

Options

A. 4.5 s
B. 5.0 s
C. 4.0 s
D. 3.5 s

Answer

B

Explanation

The length of current at any instant in an L-R circuit is given by `i=i_(0)(1-e^((-Rt)/(L)))` and the the time in which the current in the L-R circuit rises to `63%` of its maximum value is known as its time constant and is given by `t=(L)/(R)=(2.5)/(0.5)=5sec`.