Question

A current of I ampere flows in a wire forming a circular arc of radius $r$ metres subtending an angle $\theta$ at the centre as shown. The magnetic field at the centre $O$ in tesla is

• A. $\frac{\mu_{0} I \theta}{4 \pi r}$
• B. $\frac{\mu_{0} I \theta}{2 \pi r}$
• C. $\frac{\mu_{0} I \theta}{2 r}$
• D. $\frac{\mu_{0} I \theta}{4 r}$

Answer 1

Answer: (A)

$B=\frac{\mu_{0} I}{2 r} \times \frac{\theta}{2 \pi}=\frac{\mu_{0} I \theta}{4 \pi r}$