Capacitors

A capacitor is a device that stores an electric charge, with a negative net charge on one side and a positive net charge on the other. The typical capacitor has two conducting plates with an electric field in between them. Wires are connected to both sides of the plates which allow charges to pile up on the plates themselves. Usually, an insulator is inserted between both plates like a dielectric, which we'll get into later.

This gives us our equation for capacitance and also defines it if we rearrange the equation for C, the capacitance.

This tells us that capacitance is measured in the coulombs of charge on the plate per applied volt from the battery, effectively telling us how effective a capacitor is at storing energy through charges.

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The capacitance itself is similar to the resistance in Ohm's Law. It acts more like a relative constant of proportionality rather than a quantity subject to change. The capacitance of the capacitor has many different equations depending on the geometry of the conductors, but the most common equation is the one used for a parallel-plate capacitor, given a

where epsilon-naught, the permittivity of vacuum, is given above as the constant. A is the area of the two plates and d is the distance between them. Permittivity is the measure of a substance's ability to store electrical potential energy in an electric field.

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A dielectric is an insulator that can be inserted between the two conducting plates in a given capacitor. This allows for the electric field to be much more intense while also not letting the conductors come into electrical contact with one another.