12th PHYSICS chapter 1 ELECTRIC CHARGES AND FIELDS DETAILED ONE SHOT FOR BOARDS 2026 BY MUNIL SIR

12th PHYSICS chapter 1 ELECTRIC CHARGES AND FIELDS DETAILED ONE SHOT FOR BOARDS 2026 BY MUNIL SIR - Note

**1. Summary**

This video by Munil Sir is a detailed one-shot lecture on the Electric Charges and Fields chapter for the 12th-grade Physics syllabus, particularly geared towards the 2026 board exams. It covers the chapter comprehensively, from basic concepts to problem-solving. Munil Sir emphasizes the importance of actively taking notes and promises to cover case-based, competency-based, and latest pattern questions, and also covers previous year questions. The video encourages students to participate by commenting and provides links to his website, app, and practice book recommendations.

2. Key Takeaways

* **Chapter Focus**: Covers electric charges and fields from a basic to advanced level.

* **Goal**: To prepare students for the 2026 board exams and beyond.

* **Content**: Includes detailed concepts, numerical problems, and previous year questions.

* **Approach**: The lecture is delivered to encourage active note-taking.

* **Resource Recommendations**: Links to a website, app, and practice books for practice.

* **Key Concepts**:

* Electric Charge: A fundamental property of electrons and protons.

* Charging Methods: Includes friction (rubbing).

* Key Properties of Charges:

* Additivity of Charge: Charges can be added algebraically.

* Conservation of Charge: Charge is conserved in an isolated system.

* Quantization of Charge: Charge exists in discrete multiples of the elementary charge.

* Electric field & concept

* **Emphasis**: Importance of hard work and active learning by making notes.

3. Detailed Notes

* **Introduction**:

* Video targeted to Class 12th Physics board 2026

* Pdf available

* Details of the topics covered, previous year questions.

* Links provided (website, app, practice books, social media)

* **Electric Charge**:

* Defining Electric Charge: Intrinsic property of matter (electrons, protons) that leads to attraction and repulsion.

* Symbols: Q, q.

* Types of Charges: Positive and Negative.

* Unit: Coulomb (C).

* *Fundamental Law of Electrostatics*: Opposite charges attract, like charges repel.

* Key Properties of Electric Charge:

* Charge is an intrinsic property of matter.

* The electric charge is a fundamental property of a particle (electron, proton).

* Electric charge is quantized.

* Charge can be an integer multiple of the elementary charge.

* **Electron** and **Proton:** Fundamental Particles with Charges

* **Electron**: Charge = -1.6 x 10-19 C (Magnitude).

* **Proton**: Charge = +1.6 x 10-19 C (Magnitude).

* Magnitude (value) are the same, the nature (positive or negative) is opposite.

* **Smallest Value of Charge**: 1.6 x 10-19 C.

* **Types of Charges**: Positive and Negative charges.

* Examples of Positive, Negative, and Neutral Bodies:

* A charged body is a body that has either a deficit or an excess of electrons and has a non-zero net charge

* Positive charge: when the body has a lack of electrons.

* Negative Charge: when the body has excess electrons.

* Neutral body : if the number of electrons equals the number of protons, then no net charge, and it is neutral.

* **Basic Properties of Charge**:

* **Additivity of Charge:** Charges can be added algebraically (like scalars).

* When Q1 + Q2 = 0 (equal and opposite in nature).

* **Conservation of Charge:** In an isolated system, charge cannot be created or destroyed.

* Example: If 3 charges are present (q1, q2, q3 ) at a point ABC. after some time, the total charge is the same

* **Quantization of Charge:** Charge on any body is always an integer multiple of the elementary charge (q= n*e).

* **Method of Charging**:

* **Charging by Friction (Rubbing):**

* Charging by rubbing one material with another

* When two objects made of different materials are rubbed against each other, charges can be transferred between them.

* **Explanation**: Electrons can be transferred between the materials due to their varying electron affinities.

* **Result**: One object becomes positively charged (losing electrons), while the other becomes negatively charged (gaining electrons).

* Example: Friction leads to the separation of charges between two materials, one object gains electrons, and the other loses electrons.

* Example: One object will have more positive charges. The other gets more negative charges.

* **Important**: only electrons are responsible for this transfer.

* Charging by conduction

* **Coulomb's Law**:

* This is the next major topic and is a very important concept for exams.

* Statement: The force between point charges is proportional to the product of the charges and inversely proportional to the square of the distance.

* This is the first law of charges.

* Coulombs law tells us about force between the charges.

* F = k \* q1 \* q2 / r² where q1 & q2 are point charges, and r is the distance between them.

* where k is the electrostatic force constant.

* The value of K is 9 \* 10 power 9

* The force is attractive (opposite charges) or repulsive (like charges).

* **Difference between Mass and Charge**:

* **Mass**

* Only leads to attraction.

* Always present.

* Changes with speed.

* **Charge**

* Attraction or repulsion possible.

* Can be zero.

* Does not change with speed.

* **Vector Form of Coulomb's Law**:

* This section deals with forces between multiple charges.

* *Important points*:

* The force is independent of the presence and absence of other charges.

* The force between two charges is independent of other charges in the system.

* Coulomb’s force is a central force.

* Coulomb force obeys Newton’s third law.

* **Electrostatic Shielding**:

* Electrostatic shielding is the phenomenon where the electric field inside a conductor is zero.

* This is because the charges in the conductor will rearrange themselves to cancel out the external electric field.