Electric Field and Potential in Two Dimensions

In this simulation, you can explore the concepts of the electric field
and the electric potential, in a two-dimensional situation. You can turn
on 1 to 5 charged particles, and move a test charge around the plane
near these charged particles to sample both the electric field and the
electric potential, produced by the charged particles, at various
points. You can also turn on a grid of field vectors, which show the
direction and, qualitatively, the magnitude of the field at a grid of
equally spaced points in the plane in which the charged particles are
located.

Here are some facts about the electric field from point charges:

• the magnitude of the electric field (E) produced by a point charge
  with a charge of magnitude Q, at a point a distance r away from the
  point charge, is given by the equation E = kQ/r2, where k
  is a constant with a value of 8.99 x 109 N m2/C2.
• the direction of the electric field produced by a point charge is away
  from the charge if the charge is positive, and toward the charge if
  the charge is negative.
• electric field is a vector, so when there are multiple point charges
  present, the net electric field at any point is the vector sum of the
  electric fields due to the individual charges.

 Here are some facts about the electric potential from point charge

• the electric potential (V) produced by a point charge with a charge of
  magnitude Q, at a point a distance r away from the point charge, is
  given by the equation: V = kQ/r, where k is a constant with a value of
  8.99 x 109 N m2/.
• electric potential is a scalar, so when there are multiple point
  charges present, the net electric potential at any point is the sum of
  the electric potentials due to the individual charges.