physics-mechanics

The answer is A. (1) only.


(1) Like charges repel. Therefore, P and Q must carry like charges.


(2) For the two conducting spheres, it is not necessary for them to be oppositely charged such that they attract each other. As long as they are not carrying the same sign of charge, they will attract each other, even though one of them is neutral.

For they carry unlike charges, of course they will attract each other.

When one of them is charged and the other is neutral, the face of the neutral sphere near the charged sphere will induce opposite charges, in which the like charges repel to the opposite side of the neutral sphere, and they will attract each other due to difference in electrostatic forces.


(3) P and Q are identical, that is they have the same masses. Electrostatic forces between them are action and reaction pair. So, the electrostatic forces acting on them are equal in magnitude. Hence, the angle of inclination of the two spheres should be the same as shown in the figure, but the charges on them are not necessary be the same in amount.