The electric field exerts a force on the test charge in a given direction. A test charge is a positive electric charge whose charge is so small that it does not significantly disturb the charges that create the electric field.

Now consider placing a test charge in the field. The electric field extends into space around the charge distribution. The charge distribution could be a single point charge a distribution of charge over, say, a flat plate or a more complex distribution of charge. If you know the electric field, then you can easily calculate the force (magnitude and direction) applied to any electric charge that you place in the field.Īn electric field is generated by electric charge and tells us the force per unit charge at all locations in space around a charge distribution. Michael Faraday, an English physicist of the nineteenth century, proposed the concept of an electric field. For example, the gravitational field surrounding Earth and all other masses represents the gravitational force that would be experienced if another mass were placed at a given point within the field. The concept of a field is very useful in physics, although it differs somewhat from what you see in movies.Ī field is a way of conceptualizing and mapping the force that surrounds any object and acts on another object at a distance without apparent physical connection. You may have heard of a force field in science fiction movies, where such fields apply forces at particular positions in space to keep a villain trapped or to protect a spaceship from enemy fire. Explain that electric fields are very similar to gravitational fields. Describe how gravity can be thought of as a field that surrounds a mass and with which other masses interact. Ask students whether they have seen movies that use the concept of fields as in force fields.

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