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. $\frac{{\mu }_{0}I\theta }{2r}$
• D. $\frac{{\mu }_{0}I\theta }{4r}$

Answer 1

The correct option is A $\frac{{\mu }_{0}I\theta }{4\pi r}$

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