Q. If the number of turns in a coil becomes doubled, then it self inductance will be
A) Double
B) Halved
C) Four times
D) Unchanged
Explanation
(c) From formula
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ L = \frac{\phi}{i} = \frac{\mu_{0}N^{2}A}{2r} = \frac{\mu_{0}N^{2}\pi r^{2}}{2}r$
$\Rightarrow \ \ \ \ \ \ \ \ L \propto N^{2}$
So, if N is doubled, self inductance will be four times.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.