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When is there a repulsive force between two charged objects?

A:

Quick Answer

A repulsive force arises between two charged objects having the same charge polarity. Like-positive charges and like-negative charges repel one another. Meanwhile, opposite charges attract.

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Full Answer

For like-electrical charges, the magnitude of the repulsion force between the two charges is directly proportional to the product of the two charge quantities, usually expressed in coulombs and inversely proportional to the square of the distance between them. These mutually repulsive forces obey Newton’s third law, where the force on each charge is equal in magnitude and opposite in direction to the force on the other charge. The magnitude of the repulsive force is also inversely proportional to the permittivity, an indicator of the electrical field lost in polarizing the medium. The larger the permittivity, the more the medium polarizes in the presence of an electric field and the smaller the magnitude of the electric field that reaches the second charged body from the first.

A similar repulsion arises between the like-poles of a magnet; north poles repel other north poles and south poles repel other south poles. The repulsion between two like-magnetic poles is again inversely proportional to the square of the distance between them, but it is inversely proportional to the magnetic permeability, the analogue of electrical permittivity for magnetism.

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