Static electric ﬁelds arise from electric charges, electric ﬁeld lines beginning and ending on electric charges. Thus the presence of the ﬁeld indicates the presence of equal positive and negative electric charges on the two plates. In this article we will discuss about capacitance and factors affecting capacitance
The property of a capacitor to store electric charge is called capacitance. The capacitance of a capacitor is defined as the amount of charge required to create a unit potential between its plates.Hence, capacitance is the charge required per unit potential difference.
Unit of Capacitance
The unit of capacitance is Farad. It is denoted by capital letter F.
One farad is defined as the capacitance of a capacitor which requires a charge a one coulomb to establish a potential difference of one volt between its plates.
One farad is too large for practical purposes. Hence much smaller unit like microfarad (μF), nanofarad (nF) and picofarad are generally employed.
We can also defined a capacitance, it is the property which opposes any change of voltage across it.
Factor Affecting Capacitance
The greater the area of capacitor plates, the larger is the capacitance of the capacitor and vice-versa. It is because larger the plates, the greater the charge can hold for a given potential difference and this results, greater will be the capacitance.
Distance between the plates
The capacitance of a capacitor is inversely proportional to the distance between plates. The smaller the distance between two plates, the greater will be the capacitance and vice-versa. When the plates are brought closer, the electrostatics field is intensified and hence capacitance increases.
Relative permittivity of dielectric
The greater the relative permittivity of the dielectric material, the greater will be the capacitance of the capacitor and vice-versa. It is because the nature of dielectric affects the electrostatic field between the plates and hence the charge that accumulates of the plates.