Q. A closely wound coil of 100 turns and area of cross-section $1\ cm^{2}$ has a coefficient of self-induction $1\ mH$. The magnetic induction in the centre of the core of the coil when a current of $2A$ flows in it, will be
A) $0.022\ Wbm^{- 2}$
B) $0.4\ Wbm^{- 2}$
C) $0.8\ Wbm^{- 2}$
D) $1\ Wbm^{- 2}$
Explanation
(a) $B = \frac{\mu_{0}Ni}{2r} = \frac{4\pi \times 10^{- 7} \times 100 \times 2 \times \sqrt{\pi}}{2 \times 10^{- 2}} = 0.022\ wb/m^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.