Q. An arc of a circle of radius $R$ subtends an angle $\pi/2$ at the centre. It carries a current $i$. The magnetic field at the centre will be
A) $\frac{\mu_{0}i}{2R}$
B) $\frac{\mu_{0}i}{8R}$
C) $\frac{\mu_{0}i}{4R}$
D) $\frac{2\mu_{0}i}{5R}$
Explanation
(b) $B = \frac{\mu_{0}}{4\pi}\frac{\theta i}{r} = \frac{\mu_{0}}{4\pi} \times \frac{\pi}{2} \times \frac{i}{R} = \frac{\mu_{0}i}{8R}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.