San José State University
Thayer Watkins
Silicon Valley
and Tornado Alley

How the Force on a Charged Particle
Due to another Charged Particle is Exerted


It is widely believed among physicists that the force exerted by one particle upon another has to be carried by a massless, chargeless particle. For the electrostatic force the force-carrying particle is the photon. This presents the image of a charged particle continuously radiating photons. For some strange reason this notion seems never to be questioned. Energy considerations alone makes this implausible.

An alternate is readily available. When a charged particle is created its field is simultaneously created; the particle and its field are one single entity.

The force F on a particle of charge Q at a point X where the field intensity ls E is

F(X) = Q*E(X)

Whether that force is an attraction or a repulsion between the two particles\ depends upon the sign of Q and the sign of the field intensity E.

Another way of viewing the situation is that the distant particle creates a field of potential energy V(X). The field intensity E is the gradient of V(X). Thus

F(X) = Q*∇V(X)

For a concrete illustration consider a small object resting in a conical hole in the ground. The object is subject to a force based upon the gradient of the surface of the hole

The object feels that force even though there are no force-carrying particles emanating from the center of the hole.

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