Introduction
Electric charges are present in the materials that are charged with the help of friction, conduction or induction. Due to these charges an electric field is generated near them. You must be knowing that like charges in an electric field repel each other while unlike charges attract each other. But what happens when charges move around in a body? Is there any method to store the charges developed in a body?
Here, you will get answers to all your doubts and queries related to charges and electricity. You will know about two new concepts that are: Electrostatic Potential and Capacitance.
Electrostatic Potential
The electrostatic potential energy refers to the energy stored by a nonpolar molecule when it has an electric charge on its atoms. The higher the voltage difference, the higher the stored energy.
The amount of work done per unit positive test charge or in moving the unit positive test charge from infinite to that point, against the electrostatic force without acceleration, determines the electrostatic potential at any position in an electric field.
Electrostatic Potential, V= Work done / charge = W / q
SI unit = Volt, 1V= 1J/C
Electrostatic Potential Difference
The electrostatic potential difference is the voltage difference between two locations in a static electric field. It is measured in volts.
Suppose there are two points A and B, therefore the potential difference between these points is given by
VB  VA = WAB / q0
Where, W is the work done to bring charge from A to B.
Additionally, the potential difference between two points in an electric field—i.e., the line integral of the electric field from initial position A to final position B along any path—is referred to as.
VB – VA = 
·Work done by the electric field is independent of the path, therefore the potential different remains same for any path followed to bring the charge from A to B.
Electrostatic Potential due to a Point charge
V = 1/(4π ε 0) * (q/r)
· For a positive charge the electrostatic potential is positive and vice versa.
· A positive charge is driven from areas of higher potential to places of lower potential when it is placed in an electric field. A negative charge, on the other hand, encounters a force that propels it from a lower potential to a higher one.
Electrostatic Potential due to an Electric Dipole
An electric dipoles electrostatic potential at any point P whose position vector is r relative to the dipoles midpoint is given by
V = 1/(4π ε 0) * (p cos θ / r2)
Here, θ is the angle between r and p.
At any point P situated within a thin charged spherical shell with charge q and radius R, there is an electrostatic potential

Inside = V = 1/(4π ε 0) * (q / R)

On the surface = V = 1/(4π ε 0) * (q/ R)

Outside = V = 1/(4π ε 0) * (q / r), where r>R
Here, r is the distance from the center of the shell.
Question: How can we find electrostatic potential at different surfaces of any body, for example cylinder etc?
Answer: For finding more about electrostatic potential and its significance, you can visithttps://youtube.com/channel/UCoqI7C9rI2UbFPITF2bPgnQ.
Equipotential Surfaces
Surface having equal electrostatic potential at all points is called equipotential surface.
These are of so much importance and you can learn more about them on https://youtube.com/channel/UCoqI7C9rI2UbFPITF2bPgnQ.
Capacitance
The property of a body to store electrostatic energy i.e., storing charge is referred to as Capacitance.
The magnitude of the electrostatic potential energy stored in a body is directly proportional to the equivalent capacitance of that body.
Capacitance = Charge / voltage = Q / V
SI unit = Faraday, 1F= 1C/V
Capacitors
A capacitor is an electrical component in which the plates may be made of conductive foil, paper, plastic film and other materials. The plates are separated by a dielectric material such that they are charged to different potentials and with the applied electric field, charges will move between them.
Types of Capacitors
1. Parallel Plate Capacitor: In this type of capacitor, the capacitor is formed by two plates that are in parallel with one another.
Capacitance of parallel plate capacitor, C = ε0 * (A/d)
Where, A= Area of the plate, d= distance between the plates
2. Spherical Capacitor: This type of capacitor is formed by two concentric spheres and these spheres are filled with an insulator.
Capacitance of spherical capacitor, C = 4π ε 0 (R1R2 / R1 – R2)
Where R1= inner radius, R2= outer radius.
Capacitors in Series
For 2 capacitors in series having capacitance C1 and C2, net capacitance C will be,
C = 1/C1 + 1/C2
Or, C = C1*C2/ C1+ C2
Capacitors in Parallel
For two capacitors connected in parallel to each other with capacitance C1 and C2, net capacitance C will be
C = C1+C2
To learn about mixed combinations of capacitors in series and parallel, you can visit our channel https://youtube.com/channel/UCoqI7C9rI2UbFPITF2bPgnQ.
Factors affecting Capacitance
1. Dielectric: The permittivity of the dielectric has a direct relationship with capacitance: the higher the permittivity, the higher the capacitance; conversely, the lower the permittivity, the lower the capacitance.
2. Plate Spacing: It has an inverse relation with the capacitance i.e., more the distance less the capacitance and vice versa.
3. Area of the plates: Area of the plates has a direct relation i.e., greater the area greater is the capacitance and vice versa.
Applications of Capacitors
1. Capacitors are used for storing energy or charges in various electronic devices such as radio, cameras, mobile phones etc.
2. When charged, capacitors block DC signals and only allow AC signals to pass. By separating or decoupling various components of electrical circuits, this capacitor effect helps to increase efficiency by lowering noise.
3. Capacitors are employed as sensors to track a range of factors, such as fuel levels, mechanical strain, and humidity.
These are some of the applications of the capacitors. They are of much importance to us in our daily life. To explore more about these, you must visit our channel https://youtube.com/channel/UCoqI7C9rI2UbFPITF2bPgnQ.