Field - Force - Potential

Learning objectives

To show the existence of an electric field at any point even when there is no test charge.
To illustrate how a single charge will experience a repulsive or attractive force due to the presence of another single fixed charge.
To explain the link between force, field and potential (energy).
To view the orthogonality between the equipotentials and the electric field.
To observe that the electric field always points in the direction of decreasing potential.

The field is created by the fixed charge at any point, whether or not there is a test charge.

A force will exist only if you place a charge on this pre-existing electric field. Remember a charge never experiences its own electrical field.

The field is orthogonal to the equipotentials at any point and always points in the direction of decreasing potential. The spherical symmetry of this charge distribution is revealed by its spherical equipotentials.