How Capacitors are Connected

The foundation of a circuit depends on the three fundamental electronic components. They are the resistors, inductors, and capacitors. Capacitors are devices that have the ability to store energy, much like a regular electric battery. The size of a capacitor varies according to its purpose. In this study material, you’ll learn the meaning of a capacitor, the working as well as the capacitance of a capacitor, and its applications. 

Introduction to Capacitors 

A capacitor is a component used to store electric charge. It consists of two metallic plates (also known as conductors) separated by an insulating material. The insulating material used here can either be plastic, glass or ceramic. The insulating layer present between the metallic plates is known as the dielectric. 

Upon connecting the metallic plates of the capacitor to the two terminals of an external battery, they will begin to accumulate positive charge and negative charge, respectively. You can connect the capacitor in either series or parallel in a circuit. 

How does a Capacitor work?

When you connect the capacitor to a Direct Current circuit, the charge accumulated on the metallic plates causes the voltage across them to increase but limits the current. It is because the dielectric used is an insulating material. On the other hand, when a capacitor is connected to an Alternating Current circuit, the current flow will not get affected, and it will easily pass through the capacitor. 

The Capacitance of a Capacitor 

As discussed above, a capacitor has two conductors separated by an insulator. 

Let the charges of the two conductors be Q1 and Q2, and their potentials be V1 and V2, respectively.

In practice, the charges of the two conductors will be Q and -Q.

The potential difference between the two conductors is V= V1- V2. You can now charge the two conductors by connecting each of the metallic plates to the two terminals of a charging battery. The charged metallic plates create an electric field in the region between the two conductors. The electric field created is directly proportional to the charge Q. The potential difference, denoted by V, is the work done per unit positive charge. The charge Q is directly proportional to the potential difference V. Hence, the ratio QV is given by, 

C = QV

Where C is a constant and is the capacitance of the capacitor. 

The SI unit of the Capacitance is Farad, named after the eminent scientist Michael Faraday.

1 Farad is equivalent to 1 coulomb volt-1. In other words, 1F = 1C V-1. 

A capacitor can only store a limited amount of charge to prevent leaking. Since Farad is a big unit, the sub-multiples of Farad – Microfarad, Nanofarad, and Picofarad are used as the standard units of capacitance. 

• 1 Microfarad (1F) = 10-6F
• 1 Nanofarad (1nF) = 10-9F
• 1 Picofarad (1pF) = 10-12F

The capacitance of a capacitor is dependent on the size, shape, and distance of the conductors. Sometimes, the insulating material used in the capacitor can also affect the capacitance.

A higher potential difference will lead to a stronger electric field between the conductors. The capacity of the dielectric medium to withstand maximum electric field without breaking down is called its dielectric strength. The dielectric strength for air is about 3 × 106 Vm-1.

For a capacitor to store maximum charge without leaking, its capacitance should be large enough so that the potential difference (V) and the electric field does not break down. 

Applications of Capacitors 

The capacitor is a crucial part of any electronic device and has several applications. There are different types of capacitors available, and the right choice of the capacitor determines its performance. Given below are some applications of capacitors.

• The capacitors with high capacitance values are known as Supercapacitors. It is used in buses, cars and cranes. Super capacitors are also used for memory backup and regenerative braking. 
• Electrolytic capacitors are polarised capacitors that offer larger capacitance values. They are used in audio coupling and decoupling applications and in power supplies that have a low-frequency limit. 
• Ceramic capacitors are generally cheap, and their applications are found in high-frequency circuits like audio to RF. Ceramic capacitors are also known as disc capacitors. 

Conclusion

Capacitors are components used in electronic circuits to store energy. In a capacitor, two conductors separated by an insulator (called a dielectric) store energy. Capacitors come in different sizes depending on the amount of charge they hold. Here, we studied how capacitors work, steps to find the effective capacitance and the various applications of capacitors.