Question

The magnitude of magnetic induction at mid point $O$ due to current arrangement as shown in Fig will be

• A. 0
• B. $\frac{{\mu }_{0}I}{\pi a}$
• C. $\frac{{\mu }_{0}I}{2\pi a}$
• D. $\frac{{\mu }_{0}I}{4\pi a}$

Answer 1

Answer: (B)

Magnetic field due to current in BC and ET are outward at point ' $O$ '
$B_0=\frac{{\mu }_{0}i}{4\pi r}+\frac{{\mu }_{0}i}{4\pi r}=\frac{{\mu }_{0}i}{2\pi r}=\frac{{\mu }_{0}i}{\pi a}$