Question

A circular coil of N turns is wound around the central plane of a solid sphere which rests on an inclined plane of angle $\theta$. Find the strength of the vertical magnetic B such that the sphere is in equilibrium.

• A. $\frac{mgtan\theta }{Ni\pi R}$
• B. $\frac{mgcot\theta }{Ni\pi R}$
• C. $\frac{mg}{Ni\pi R}$
• D. $\frac{mgsin\theta }{Ni\pi R}$

Answer 1

The correct option is C $\frac{mg}{Ni\pi R}$


$mgsin\theta R=MBsin\theta$
$mgR=\left(Ni\pi R^2\right)B$
$B=\frac{mg}{Ni\pi R}$