The Electric Field, also called the electrostatic fi eld, the electric field is not as commonly known per se as the magnetic fi eld. In the same way that current is connected to the magnetic field, voltage is connected to the electric field. That leads to a good rule of thumb to remember:  Current is magnetic and voltage is electric .

The electric fi eld comes from electric charges, both positive and negative. In a way that is analogous to the way like poles on magnets repel and opposite poles attract, like charges repel and opposite charges attract. Any molecule or atom can be neutral (no net charge), positively charged, or negatively charged.

The accumulation of these charges is what is known as voltage. One way to think of it is that the charges are the voltage making the electric field, and movement of those charges is called current and creates the magnetic field.

Similarly to the way an inductor is a way of concentrating a magnetic field, a capacitor is a way of concentrating an electric field. Capacitors are made by two collectors or plates separated by a material that will not conduct electricity, also known as a dielectric.

Because of the dielectric, current or actual charges cannot fl ow or move across the capacitor, all the charges build up on one side of the cap, kind of like a 50-car pileup on the freeway.

As the charges pile up on one side, the electrostatic fi eld builds up, causing all the like charges on the other side of the cap to go rushing away (remember how like charges repel). Once it all comes to rest, there is an equal number of opposite charges on the other side of the cap. In this way the capacitor stores a charge of voltage on the plates of the capacitor.

How much charge a cap can store in an electric field is a function of the area of the plates. The amount of voltage it can store is dependent on the strength of the dielectric. If you exceed the capability of the insulation, the dielectric will break down and a charge will cross the gap. The same thing happens on a stormy day.

During a thunderstorm charges build up in the clouds and the ground in the same way they do on either side of a capacitor. A lightning strike is a large-scale version of what happens when the insulation or dielectric in a capacitor breaks down.

In the same way current creates a magnetic fi eld, voltage creates an electric field. Just as the magnetic fi eld can store energy, the electric fi eld can also store energy. As the magnetic fi eld dissipates, it tries to maintain current. As the electric field dissipates, it tries to maintain voltage. Voltage and electric fields are closely connected.

Thumb Rules
An inductor stores energy in a magnetic field.
A capacitor stores energy in an electric field.
Current is magnetic.
Voltage is electric.

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