The voltage between the plates and the charge held by the plates are related by a term known as the capacitance of the capacitor. Capacitance is defined as: The larger the potential across the capacitor, the larger the magnitude of the charge held by the plates.
When a voltage V is applied to the capacitor, it stores a charge Q, as shown. We can see how its capacitance may depend on A and d by considering characteristics of the Coulomb force. We know that force between the charges increases with charge values and decreases with the distance between them.
A capacitor consists of two parallel conducting plates separated by an insulator. When it is connected to a voltage supply charge flows onto the capacitor plates until the potential difference across them is the same as that of the supply. The charge flow and the final charge on each plate is shown in the diagram.
The best way to know the characteristics of a capacitor is to figure out the family the capacitor belongs to whether ceramic, film, plastic, or electrolytic. Most capacitors have the same capacitance value, they may have different voltage ratings.
By applying a voltage to a capacitor and measuring the charge on the plates, the ratio of the charge Q to the voltage V will give the capacitance value of the capacitor and is therefore given as: C = Q/V this equation can also be re-arranged to give the familiar formula for the quantity of charge on the plates as: Q = C x V
The higher the value of capacitance, the more charge the capacitor can store. The larger the area of the plates or the smaller their separation the more charge the capacitor can store. A capacitor is said to be “Fully Charged” when the voltage across its plates equals the supply voltage.