Question

The force between two charges at a distance ‘r’ is ‘F’. What will happen to the force if a metal rod is inserted between the charges?

Answer 1

That depends on the sign of the charges and the placement of the metal plate. If the charges are equal and opposite, and the metal plate placed midway between them, then there is no effect on the force on either charge. However, if the charges are equal and the same sign, the introduction of a metal plate between them will decrease the repulsive force.