Capacitance and Capacitor

The capacitor is an electricity storage tool made up of two conductors very close together and insulated from each other. A parallel plate capacitor is a good example of a capacitor with electrostatic shielding. It works on the principle that the capacitance of a conductor will increase dramatically whilst drawing close to a grounded conductor. Capacitance is nothing but the potential of a capacitor to store energy within the shape of an electrical field. We define the potential energy of a test charge q in terms of the work done on the charge q. This work is proportional to q since the force at any point is qE, where E is the electric field at that point due to the given charge configuration.

The relation between an electric field and the potential is as follows:

• The electric field is in the direction in which the potential decreases steepest.

• Its magnitude is given by the change in the magnitude of potential per unit electric displacement normal to the equipotential surface at the point.

Factors Affecting Capacitance

3 factors affect capacitance:

• The dimensions of the conductor and dielectric and the space between them

• The effect of dielectric on capacitance also exists. The larger the conductors, the larger the capacitance. The smaller the gap, the larger the capacitance. 

• When a voltage is executed to the conductors, positive and negative charges gather on each conductor. By alternating the voltage on the conductors, the charged additional alternates are generated proportional to the capacitance. 

Capacitance of a Parallel Plate Capacitor

• A parallel plate capacitor is an arrangement of two steel plates connected in parallel, separated from each other through distance. 

• The dielectric does not permit the flow of electricity through it because of its non-conductive property.

• The parallel plate capacitor is created when two parallel plates are linked across a battery. The plates are energised, and an electric field is formed between them.

The direction of the electric field is the direction of the flow of positive charge. Capacitance is called the limitation of the storage capacity of the electric charge. Every capacitor has its capacitance. Area A has two metallic plates in a typical parallel plate capacitor, separated by the distance d.

C = kєoA/d

Here, єo is permissive of free space. (8.854 × 10−12 F/m)

k represents the similar permittivity of dielectric material

d is the separation between the plates.

A is the area of plates.

Series combination of capacitor:

In a series combination, capacitors must have the same charge.  Let’s consider three capacitors connected in series in a circuit and their capacitance is C1 , C2 and C3. So equivalent capacitance will be 

1/Ceq = 1/C1 + 1/C2 + 1/C3. 

Parallel Combination of Capacitors

In a parallel combination of capacitors, the potential voltage difference among each of the capacitors remains the same. Let’s consider three capacitances, C1, C2 and C3, which are connected in a parallel circuit, and one voltage source VAB is also attached in this circuit. The formula of parallel combination is given by 

Ceq= C1 + C2 +C3+…….+Cn.

Capacitance of a Spherical Capacitor

• The capacitance of a spherical capacitor is the capacitance of a spherical or cylindrical conductor and can be acquired by evaluating the voltage distinction between the conductors for every individual rate. 

• Formula: C = VQ.

How Capacitors Work

• In a sense, capacitors are chunk-like batteries. A capacitor is an electric device that absorbs and stores energy from a battery. 

• The terminals are connected to two metal plates on the inside. They are divided by a non-conducting material called a dielectric. When a capacitor is engaged, it swiftly discharges electricity in a split second.

• Capacitors can be from the smallest plastic capacitors in pocket calculators to ultracapacitors, including electricity commuter buses.

Energy Stored in a Capacitor:

Consider a parallel plate capacitor of capacitance C. A small charge dq moves from one plate to another plate, so work done to move this charge can be written as

dW = Vdq

dW = (q/C)dq

Here V is the voltage of the capacitor.

For large charge transfer work done will be

W = 0Q(q/C)dq

W = Q2/2C

This work done is equivalent to energy stored in capacitor i.e U = W

U = Q2/2C = (½)CV2 = (½)QV

Conclusion

A capacitor is a two-terminal electrical component that may retain energy in the form of electrical charges. It is made up of two electrical wires separated by a certain distance. Capacitors are used for energy storage and power conditioning, as sensors, and for signal processing. A capacitor is an indispensable part of electronic equipment and is thus almost invariably used in an electronic circuit. Electrostatic shielding involves defending any whole area inside a conductor to lower costs or electric-powered problems.