Question

A wheel having mass m has charges $+q$ and $-q$ on diametrically opposite points. It remains in equilibrium on a rough inclined plane in the presence of uniform vertical electric field $E$. The value of $E$ is:

• A. $\frac{mg}{q}$
• B. $\frac{mg}{2q}$
• C. $\frac{mg\tan \theta }{2q}$
• D. $None$

Answer 1

The correct option is A $\frac{mg}{q}$

To be the wheel in equilibrium the net force and thenet torque on it must be zero.

$qE=mg$ (on balancing forces)

$E=\frac{mg}{q}$