Electric potential energy

There is not much difference between electric potential energy and potential energy. An object has potential energy as a result of its location. If you try to lift an object, the object is located in a force field and that force field is gravity. When the object is lifted to a certain height it has gravitational potential energy. If you compress a spring, it will also store potential energy.

In both cases, this potential energy that the object has stored has the ability to do work when released. 

The more you compress a spring, the higher the stored potential energy.

Take a look at the spring above. Suppose that the spring is not compressed at all. This is the case for the first image on top.

In this case, the potential energy is 0. For the figure in the middle, the spring is compressed as you can see. Therefore the spring will store some potential energy.

However, for the last figure at the bottom, suppose that the spring is compressed all the way or almost all the way. The potential energy will then be at its maximum or close to it.

Similarity with the electric potential energy

An object that is charged can have potential energy as a result of its location in an electric field. Since the object is now located in an electric field, we call this energy electric potential energy.

The image above shows a small positive charge that will be moved closer and closer to the positively charged rod.

Just like work is required to compress a spring, work is required to bring the small positive charge toward the charged rod. Recall that like charges repel. That is the reason work is required to move the small positive charge toward the charged rod.

Just like more work is required to compress a spring all the way, more work will be required to bring the small positive charge as close as possible to the rod.

When you compress a spring, the spring stores energy and this energy can be called elastic potential energy. Why elastic? The word elastic may remind you of something that can be stretched. A spring can be stretched or compressed of course. This is where the word elastic came from.

When you bring a small positive charge close to a charged rod, the small charge will also store energy and this energy is called electric potential energy.

The closer the small charge is to the rod, the higher the stored electric potential energy.

Note that if the small charge is released, it will accelerate in the opposite direction away from the charged rod. This electric potential energy will be transformed to kinetic energy.