Class 12 Physics Chapter 2 Notes – Electrostatic Potential and Capacitance

Electric Charges and Fields – Class 12 Physics Chapter 2 Notes

Electrostatic Potential: The amount of work done per unit positive test charge, or in getting the unit positive test charge from infinity to that place, against the electrostatic force without acceleration, determines the electrostatic potential at any location in an electric field.

electrostatic potential
Formula for electrostatic potential

The difference in Electrostatic Potential: The quantity of work done in transporting a unit positive test charge from one place to the other spot against electrostatic force with no acceleration is described as the electrostatic potential difference between two points in an electromagnetic field (i.e. the difference of electrostatic potentials of the two points in the electric field).

When a positive charge is applied to a point, the potential is positive, and when a negative charge is applied, the potential is negative.

When a positive charge in an electric field is applied, it is subjected to a force that propels it from higher to lower potential points. A negative charge, on either hand, is subjected to a force that propels it from a lower to a greater potential.

Equipotential Surface: A surface with an Equipotentiality refers to a surface that has the same electrostatic potential at all points on it. Because of the I line charge, the form of the equipotential surface is cylindrical and the point charge is spherical.

Class 12 Physics Chapter 2 Notes
  • Equipotential surfaces do not connect since this would result in two directions of electric field E at the site of the intersection, which is not achievable.
  • In the presence of a strong electric field, equipotential surfaces are closely spaced, and conversely.
  • At every location, the electric field is normal to the equipotential surface and directed from one higher potential equipotential surface to the lower potential equipotential surface.
  • The amount of work required to move a test charge from one point of the equipotential surface to the next is zero.

Potential gradient and electric field relationship: The electric field is the one in which the potential declines the most rapidly. The variation in the magnitude of potential per unit displacement perpendicular to the equipotential surface at the location determines its value.

In an electric field, the work required to move unit positive test charge through a closed circuit is zero. As a result, electrostatic forces are conservative.


Electrostatic shielding is the process of creating a zone that is devoid of any electric fields. It occurs because there is no electric field within charged hollow conductors. A shell’s potential is constant. We may also deduce that the field within the hollow conductor will be zero in this fashion.

electrostatic shieding
The electric field inside any conductor’s hollow is zero. Only the outside face of a conductor with hollow contains all charges. (No charges have been placed in the hollow.)

Coulomb’s law: Whenever charges with opposite polarities attract one other, they generate force; if the signs are the identical, they repel one another. Coulomb’s law is a mathematical equation that attempts to define this occurrence. There’s also crucial information concerning the constant k’s fluctuation and its impact on a media.

Electric dipoles: ‘Dipoles’ are two opposed points of charges symbolised by the letters q and –q, with a space of 2a between them.

Furthermore, the notes for Class 12 Physics Chapter 2 concentrate on the effect of electric dipoles on a uniform electric field, primarily through Force and Torque, Work, and Potential Energy.

The final section of Electrostatics focuses on maximising the capability of the equations. Electric Field, Electric Potential Energy, Electric Potential, and Electric Dipole are among the subsections. You’ll find proper answers for electrostatic potential and capacitance in the papers, along with clear and crisp pictures for improved understanding.

electric dipoles - Class 12 Physics Chapter 2 Notes

Guaus’s law: The total electric flux travelling through a hypothetical closed path equals the net electric charge contained within the same closed path, according to Gauss’ Law. Because it is such a large part of the chapter, you may have to devote a bit more time to it. It then go on to talk about the qualities of conductors in regard to Gauss’s Law.

Dielectrics: Non-conducting materials are known as dielectrics. They don’t have any (or very few) charge carriers, unlike conductors.

Consider what occurs when a conductor is exposed to an electric field from the outside. The charge distribution in the conductor adapts itself as the free charge carriers travel, so that the electric field owing to induced charges resists the external field inside the conductor. This continues until the two fields balance each other out and the conductor’s gross electrostatic field is 0.

This free flow of charges isn’t conceivable in a dielectric. The external magnetic field, it creates dipole moment by expanding dielectric molecules. The net charges on the face of the dielectric produce a field that resists the external field due to the combined action of all the molecule dipole moments.

In an external electric field, a conductor and a dielectric behave differently.

Capacitors and capacitance: A capacitor is a two-conductor arrangement with an insulator between them. Charges Q1 and Q2, as well as potentials V1 and V2, are present in the conductors. In practise, the two conductors usually have charges Q and – Q, with a potential difference among them of V = V1 – V2.

Only this type of capacitor charge setup will be considered. By joining the conductors to the two terminals of a cell, the conductors can be charged in this way. Though Q is referred to as the capacitor’s charges, it actually refers to the charge on one of the conductors; the capacitor’s overall charge is zero.

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Final Thoughts – Class 12 Physics Chapter 2 Notes – Electrostatic Potential and Capacitance

With the help of subject matter specialists, Readaxis creates the Class 12 Physics Chapter 2 Notes. The notes provides a full overview of the issue as well as probable answers to the most often asked questions. Additionally, the full explanations for each subject and subsection are provided in plain language, allowing students to ace their tests with a well-rounded understanding.

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