Course Content
Class 12th Physics Chapter 1 Electric Charges And Fields
NCERT Solutions for Chapter 1 for Class 12 Physics talks about factors and topics related to Electric Charge and Fields. Some of the prominent topics covered in the Chapter are Conductors And Insulators, Charging By Induction, Basic Properties Of Electric Charge, Coulomb’s Law, etc.
Class 12th Physics Chapter 2 Electrostatic Potential And Capacitance
NCERT Solutions for Chapter 2 for Class 12 Physics talks about Electrostatic Potential in detail. The chapter revolves around relevant topics such as Potential Due To A Point Charge, Potential Due To An Electric Dipole, Potential Due To A System Of Charges, Equipotential Surfaces, etc.
Class 12th Physics Chapter 3 Current Electricity
NCERT Solutions for Chapter 3 for Class 12 Physics is an important chapter from weightage point of view. This chapter is very scoring and can be a very interesting chapter for students. The chapter talks about Electric Current, Ohm’s Law, Drift Of Electrons And The Origin Of Resistivity, Limitations Of Ohm’s Law, Resistivity Of Various Materials, etc.
Class 12th Physics Chapter 4 Moving Charges And Magnetism
Chapter 4 for Class 12 Physics can be a very scoring chapter for Class 12 students. However, it is equally complex to understand. It talks about Magnetic Force, Motion In A Magnetic Field, Motion In Combined Electric And Magnetic Fields, etc.
Class 12th Physics Chapter 5 Magnetism And Matter
NCERT Solutions for Chapter 5 for Class 12 Physics talk about topics related to Magnetism and Matter such as the Bar Magnet, Magnetic field lines, The electrostatic analogue, Magnetism And Gauss’s Law, The Earth’s Magnetism, Magnetic declination and dip, Magnetic Properties Of Materials, Diamagnetism, Paramagnetism, Ferromagnetism.
Class 12th Physics Chapter 6 Electromagnetic Induction
A very interesting and Chapter, this one in particular talks about The Experiments Of Faraday And Henry, Magnetic Flux, Faraday’s Law Of Induction, Lenz’s Law and Conservation Of Energy.
Class 12th Physics Chapter 7 Alternating Current
NCERT Solutions for Chapter 7 for Class 12 Physics talk about Ac Voltage Applied To A Resistor, Phasor-diagram solution, Analytical solution, Resonance, Oscillations, and Transformers.
Class 12th Physics Chapter 8 Electromagnetic Waves
In this chapter students will learn about Displacement Current, Electromagnetic Waves, Sources of electromagnetic waves and other such topics related to Electromagnetic Waves.
Class 12th Physics Chapter 9 Ray Optics and Optical Instruments
NCERT Solutions for Chapter 9 for Class 12 Physics talks about Reflection Of Light By Spherical Mirrors, Refraction, Total Internal Reflection and other topics related to Ray Optics.
Class 12th Physics Chapter 10 Wave Optics
NCERT Solutions for Chapter 10 for Class 12 Physics talk about Huygens Principle, Refraction and Reflection Of Plane Waves Using Huygens Principle, Refraction Of A Plane Wave, Refraction At A Rarer Medium etc.
Class 12th Physics Chapter 11 Dual Nature Of Radiation And Matter
Chapter 11 for Class 12 Physics is a scoring chapter. If learnt the concepts thoroughly, it can help students to score high marks in their Physics exam. This chapter talks about Electron Emission, Photoelectric Effect, Hertz’s observations, Hallwachs’ and Lenard’s observations, etc.
Class 12th Physics Chapter 12 Atoms
Chapter 12 for Class 12 Physics is a very interesting yet very confusing chapter for the students. It talks about topics: Alpha-Particle Scattering and Rutherford’s Nuclear Model Of Atom, Alpha-particle trajectory, Electron orbits, Atomic Spectra etc.
Class 12th Physics Chapter 13 Nuclei
NCERT Solutions for Chapter 13 for Class 12 include all answers to the questions included in the textbook. Additionally, the solutions explain topics such as Atomic Masses And Composition Of Nucleus, Size Of The Nucleus, Mass-energy And Nuclear Binding Energy, etc in detail.
Class 12th Physics Chapter 14 Semiconductor Electronics Materials Devices And Simple Circuits
Chapter 14 for Class 12 Physics Is a very scoring and interesting chapter and revolves around topics such as Intrinsic Semiconductor, Extrinsic Semiconductor, P-n Junction, Semiconductor Diode, Application Of Junction Diode As A Rectifier etc.
Class 12th Physics Chapter 15 Communication Systems
NCERT Solutions for Chapter 15 for Class 12 Physics talks about topics related to the communication systems. The important topics are Elements Of A Communication System, Basic Terminology Used In Electronic Communication Systems, etc. This is a very interesting chapter in the Class 12 Physics textbook.
Frequently asked questions (FAQs) Related to Course
Here are some frequently asked questions (FAQs) that could be relevant for your Class 12 Physics Online Course: 1. What is the Class 12 Physics Online Course offered by Free-Education (Wisdom Academy)? Our Class 12 Physics Online Course is a comprehensive learning program designed to help students excel in their CBSE Board exams. It includes chapter-wise notes, important questions, solved and unsolved previous year question papers, video explanations, interactive classes, and more. 2. Who is the instructor for this course? The course is curated and taught by Er. Mohd Sharif, an experienced educator with over 13 years of teaching Physics. He is also the founder of Wisdom Education Academy & Free-Education.In. 3. How can I access the course materials? Once you enroll in the course, you will gain access to our online learning platform. All course materials, including notes, videos, and question papers, can be accessed from there at any time. 4. Are the notes and resources provided in downloadable formats? Yes, our chapter-wise notes and other resources are available in downloadable PDF formats. This allows you to study even when you're offline. 5. How can I ask questions or clear doubts during the course? We offer doubt clearance through online classes, where you can interact with the instructor directly and get your queries resolved. You can also use our platform's messaging system to communicate with the instructor. 6. Are there regular tests to review my preparation? Absolutely, we believe in consistent evaluation. The course includes regular review tests to gauge your understanding and track your progress. 7. Can I access the course on mobile devices? Yes, our online learning platform is mobile-friendly, allowing you to access the course materials on various devices like smartphones and tablets. 8. Are there any prerequisites for enrolling in this course? This course is designed for Class 12 students studying Physics. It's tailored to cover all topics and concepts within the Class 12 Physics curriculum. 9. How can I enroll in the Class 12 Physics Online Course? Enrolling is simple. Visit our website, navigate to the Class 12 Physics Course, and follow the enrollment instructions. 10. Is there a refund policy in case I'm not satisfied with the course? Yes, we have a refund policy in place. If you're not satisfied with the course within the first 7 days, you can request a refund according to our refund policy. 11. Can I interact with other students in the course? Yes, we encourage collaborative learning. Our platform may include discussion forums or other means for students to interact and share insights. 12. Are there any additional resources provided apart from the course materials? In addition to the course materials, we may provide supplementary resources like articles, study tips, and external references to enhance your learning experience. For any other questions or clarifications, feel free to reach out to our support team at (8750387081).
Class 12 Physics Online Course: Notes, Important Questions, and Previous Year Papers
About Lesson

Introduction to Conductors

A conductor is an object or type of material that allow the flow of electrical current in one or more directions. A metal wire is a common electrical conductor.

  • Conductors contain mobile charge carriers in the form of electrons.
  • The valence electrons facilitate the flow of current in a conductor.
  • Examples of conducting materials are Human body, Metallic objects, water etc.

Electrostatics of Conductors

Conductors have loosely bound electrons to allow current to flow. In an external electric field, they drift against the direction of the field. The electrostatic field at different points in a conductor is given below.

  • Inside Conductor
    • The electrostatic field inside the conductor is zero.
    • Under no external electric field or static condition, the charge carriers are distributed evenly and there is no electric field inside.

At the surface of a charged conductor

  • The electrostatic field at the surface of a charged conductor is normal to the surface at every point.
  • For a non-normal Electric field, there is a non-zero component along the normal. Therefore, Electric field should have no tangential component in static.
  • Interior of a conductor
    • There is no electrostatic field in the interior of the conductor. All the excess charge resides at the surface.
    • Under static conditions, the excess charge resides at the surface of the conductor. On a closed surface, the electrostatic field is zero. So from gauss’s law, there is no net charge enclosed by the surface.
  • Throughout the Volume of the conductor
    • The Electrostatic potential is constant throughout the volume of the conductor and is equal to its value on surface.
    • Since, conductor has no tangential component; no work is done in moving charge within conductor and on its surface. Hence the potential is constant.

Electrostatic Shielding

Electric field inside a cavity in a conductor is always zero. Even if the conductor is charged or charges are induced on a neutral conductor by an external field, all charges reside only on the outer surface of the conductor. Hence, the any cavity of any shape and size is always shielded from outer electric influence. This is called electrostatic shielding.

electrostatic potential and capacitance
electrostatic potential and capacitance


Dielectrics are non-conducting substances having negligible number of charge carriers. In presence of an external electric field, dipole moments are induced in dielectrics by stretching and re-orienting the molecules of the dielectric. The collective dipole moment is the net charge on the surface of dielectric which opposes and reduces (does not cancel) the external field.

Some of the dielectric materials are:

  • Porcelain (ceramic), mica, glass, plastics, and the oxides of various metals.
  • Some liquids and gases
  • Dry air
  • Distilled water
  • Vacuum

Polar and Non-Polar Molecules

When multiple atoms are bonded to each other, a molecule is formed. These bonds or electron sharing arrangement can be polar (when electrons are shared unequally) and non-polar (when electrons are shared equally).

  • Various substances may have polar and non-polar molecules depending upon the charge configuration inside them.
  • A substance can be polarized from an external electric field which leads to development of induced dipole moment inside them.
Criteria Polar Non-Polar
Centers of positive and negative  charges The centers are separated even in the absence of external electric field The centers coincide
Dipole Moment Permanent dipole moment No permanent dipole moment
Examples Hydro Chloric Acid (HCl) and Water (H2O) Oxygen(O2) and Hydrogen(H2)
Dielectrics in External Electric Field The individual dipole moments tend to align with the field. They develop a net dipole moment in the direction of the field. Positive and negative charges get displaced. They develop an induced dipole moment as a restoring force against the direction of electric field.

Polarization of dielectrics

A dielectric develops a net dipole moment in the presence of an external field.The dipole moment per unit volume is called polarization and is denoted by P. For linear isotropic dielectrics (substances where induced dipole moment is in the direction of the field and is proportional to the field strength),

P = χe E

χe – electric susceptibility of the dielectric medium

electrostatic potential and capacitance
electrostatic potential and capacitance

Capacitors and Capacitance

capacitor is a system of two conductors separated by an insulator.

  • The total charge of a capacitor is zero while the conductors have charge Q and –Q.
  • A single conductor can be considered as capacitor with other conductor at infinity.
  • Electric field in the region between the conductors is proportional to the charge Q.
  • Capacitanceis denoted by, C = Q/V. It depends on:
    • Geometrical configuration (shape, size, separation) of the system of two conductors.
    • Nature of insulator/dielectric separating
  • Charge on the capacitor leaks away due to reduction in the insulating power of the intervening medium. This happens due to higher potential difference causing strong electric fields.
  • Maximum electric field which a dielectric medium can withstand without breakdown and prevent leaking of charge is called dielectric strength. Air dielectric strength is 3 x 10Vm-1.
  • SI unit of capacitance is F (Farad).
electrostatic potential and capacitance
electrostatic potential and capacitance

Parallel Plate Capacitor

A parallel plate capacitor is a capacitor with 2 large plane parallel conducting plates separated by a small distance.

  • Electric field inside the capacitor has a direction from positive to negative plate.
  • For very small‘d’, the electric field is considered as uniform. For large‘d’, the electric field is non-uniform and it bends around the corners of the plate which is called fringing of the field.
electrostatic potential and capacitance
electrostatic potential and capacitance

Effect of dielectric on Capacitance

When a dielectric is present between the plates of a parallel plate capacitor fully occupying the region, the dielectric is polarized by the electric field. The surface charge densities are considered as σp and -σp.

Dielectric constant of a substance is the factor by which the capacitance increases from its vacuum value, when the dielectric is fully inserted in between the plates of the capacitor

Combination of Capacitors – Series

Capacitors are said to be connected in serieswhen the second plate of a capacitor is connected to the first plate of the next capacitor and so on.

  • Capacitors are connected in series as per the below diagram.
  • The charge across the arrangement will remain the same.
  • The total potential drop is the sum of individual potential drops across each capacitor.
  • The inverse of total capacitance is the sum of inverse of individual capacitances.

Combination of Capacitors – Parallel

Capacitors are said to be connected in parallel when the firstand second plate of a capacitor is connected to the first and second plate of the next capacitor respectively.

  • Capacitors are connected in parallel as per the below diagram.
  • The potential across the arrangement will remain the same.
  • The total charge is the sum of individual charges across each capacitor.
  • The total capacitance is sum of individual capacitances.

Energy stored in a Capacitor

Energy is stored in the capacitor when work is done to move a positive charge from negative conductor towards the positive conductor against the repulsive force.

electrostatic potential and capacitance
electrostatic potential and capacitance


Van de graaff generator is used to generate high voltages of the order of a few million volts. This results in generation of large electric fields for experimental purposes.


electrostatic potential and capacitance
electrostatic potential and capacitance
electrostatic potential and capacitance
electrostatic potential and capacitance


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