# Capacitor types and Capacitance/Voltmeter

## Capacitor

A capacitor is a very commonly used passive component in a circuit. It has two terminals. The capacitors can store energy in an electric field, it acts as a fully charged battery.

The capacitor is made from two conducting plates kept parallel to each other and a dielectric is placed between the plates. The dielectric is made from insulating materials like glass, paper, plastic, ceramic etc. The conducting plates are made from metals like silver, aluminium etc. These plates are connected to the terminal wires.

## Working of a capacitor

When an electric current passes through the capacitor, one of the plates of the capacitor gets negatively charged and the other plate gets positively charged. The stationary charges stuck in these plates will create an electric field. Therefore, electric energy is stored in the plates just as the battery stores chemical energy. Let us discuss more on capacitor types and capacitance.

## Capacitance of a capacitor

Capacitance is the measure of the capacitors ability to store the electrical charges on the plates. The SI unit of capacitance is Farad. The capacitance is given by the equation

C = q/V

C is the capacitance

q is the charge stored in the plates

V is the applied voltage

The capacitance of the capacitor is one farad when a charge of one coulomb is stored on the plates by a voltage of one volt.

## Capacitor types

There are different types of capacitors available in the market. Each of them with different features and drawbacks.

### Ceramic capacitors

The most commonly used type of capacitor is ceramic capacitors. The dielectric of the ceramic capacitor is made from ceramic. They are very small in size and have a low capacitance. It is difficult to find a ceramic capacitor with a capacitance greater than 10μF. These capacitors or caps are suitable for high-frequency coupling and decoupling.

### Aluminium and Tantalum Electrolytic Capacitors

We get electrolytic capacitors with high capacitance. They can pack a large capacitance in a relatively small volume. The capacitance of an electrolytic capacitor ranges from 1μF to 1mF. They are used in high voltage applications.

The electrolytic capacitors are mostly polarised. They have a positive terminal called the anode and a negative terminal called the cathode. If the voltage is applied in reverse it can damage the capacitor.

### Supercapacitors

Supercapacitors can store a large amount of charge. They are designed to have a large capacitance. The drawback of these capacitors is that they cannot deal with very high voltages.

They are used to store and release energy just like batteries. They release energy much faster than a battery and have a longer lifespan.

### Other capacitors

There are many other less common capacitors like the variable capacitors, film capacitors etc.

 Do check BYJU’S pages for more details on the working of the devices like Voltmeter and Ammeter. A voltmeter is a device used to measure voltage or the potential difference between two points of the electrical circuit. The voltmeter can be both digital and analog.