Answer to Question #261596 in Electric Circuits for Samiun

Question

what must be the charge on a particles of mass 2g for it to remain stationary in the labrotary when placed in a downward directed electric field of 500NC-1

Answer 1

The force of gravity and the electric force must be in equilibrium:

$$mg=QE,\\\space\\ Q=\frac{mg}E=39.2\space\mu\text C.$$