Question

Identify the direction of the net force acting on the positive charge at point A?

• A. $\to$
• B. $\leftarrow$
• C. $\uparrow$
• D. $\downarrow$
• E. There is no net force acting on the charge at point $A$

Answer 1

The correct option is D $\downarrow$

Given:

1. there exists a region of magnetic field (direction unknown)
   
2. there is a positive point charge A whose motion is along a vertical circle

From (2) we can deduce that the magnetic force acting on A provides the necessary centripetal force to keep it in motion. And this force must be directed radially inwards.

Hence at the position of A shown in the question, the net force is directed downwards.