Q. A coil has an inductance of $2.5\ H$ and a resistance of $0.5\ r$. 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
A) 3.5 sec
B) 4.0 sec
C) 4.5 sec
D) 5.0 sec
Explanation
(d) $t = \tau = \frac{L}{R} = \frac{2.5}{0.5} = 5\ \sec$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.