PHY_聽日考啦,問一問!急急急急急急急急急急急急急急!!!

Yes, angle A = angle B

The electrostatic force acting on A by B and that acting on B by A are actually action and reaction force. So, they are the same in magnitude but opposite in direction.

Although A and B have different number of charges, it just affects the magnitude of electrostatic repulsion between them.

A and B have the same masses. And also the forces acting on them are in same magnitude. So, the tension required in the string to maintain the system in equilibrium must be the same.

Therefore, T = F/sin@, and T = mg/cos@

As F and mg are the same, @ should be the same also.