Q. The current in the windings on a toroid is $2.0A$. There are 400 turns and the mean circumferential length is $40cm$. If the inside magnetic field is $1.0T$, the relative permeability is near to
A) 100
B) 200
C) 300
D) 400
Explanation
(d) $BV = \frac{\mu_{0}\mu_{r}Ni}{2\pi r} \Rightarrow 1 = \frac{4\pi \times 10^{- 7} \times \mu_{r} \times 400 \times 2}{0.4} \Rightarrow \mu_{r} = 400$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.