Q. The inductance of a solenoid $0.5\ m$ long of cross-sectional area $20\ cm^{2}$ and with 500 turns is
A) $12.5\ mH$
B) $1.25\ mH$
C) $15.0\ mH$
D) $0.12\ mH$
Explanation
(b) $L = \frac{\mu_{0}N^{2}A}{l} = \frac{4\pi \times 10^{- 7} \times (500)^{2} \times 20 \times 10^{- 4}}{0.5}$
$= 1.25\ mH$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.