Class 12th Physics-Electric Charges and Fields-Introduction-Electrostatics Electrodynamics-Part-1.
Class 12th Physics-Electric Charges and Fields-Introduction-Electrostatics Electrodynamics-Part-1.
Here is a clear and simple explanation of Class 12th Physics – Chapter: Electric Charges and Fields (Part 1: Introduction to Electrostatics and Electrodynamics):
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Class 12 Physics – Electric Charges and Fields
Chapter 1: Introduction to Electrostatics & Electrodynamics – Part 1
What is Electrostatics?
Electrostatics is the branch of physics that deals with electric charges at rest.
In simple words: Electrostatics studies how stationary electric charges behave and interact.
What is Electrodynamics?
Electrodynamics deals with electric charges in motion and how they produce magnetic fields and electric currents.
Electric Charge – Basic Concept
➤ Definition:
Electric charge is a fundamental property of matter that causes it to experience a force in an electric field.
➤ Types of Charges:
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Positive Charge (+) — e.g., Protons
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Negative Charge (−) — e.g., Electrons
Like charges repel
Basic Properties of Electric Charge
| Property | Description |
|---|---|
| Additivity | Total charge = sum of individual charges |
| Conservation of Charge | Charge can neither be created nor destroyed |
| Quantization | Charge exists in discrete packets (q = ±ne) |
| Transferability | Charges can be transferred (e.g., by rubbing) |
Elementary charge (e) = 1.6 × 10⁻¹⁹ C
Methods of Charging a Body
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By Friction – Rubbing two objects (e.g., rubbing a balloon on hair)
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By Conduction – Direct contact with a charged body
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By Induction – Without touching, using influence of nearby charge
Coulomb’s Law (Introduction Only)
Coulomb’s law gives the force between two point charges:
F=k⋅q1q2r2F = k \cdot \frac{q_1 q_2}{r^2}
Where:
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FF = Electrostatic force
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q1,q2q_1, q_2 = Magnitude of charges
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rr = Distance between charges
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k=14πε0k = \frac{1}{4\pi\varepsilon_0} = Coulomb’s constant
Electrostatic Force vs Gravitational Force
| Electrostatic Force | Gravitational Force |
|---|---|
| Acts on charge | Acts on mass |
| Can be attractive or repulsive | Always attractive |
| Much stronger | Very weak comparatively |
Summary:
“Electrostatics deals with stationary charges and the forces between them. It forms the foundation of understanding electric fields, forces, and charge behavior.”
Next Topics in Part 2:
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Coulomb’s Law (in detail)
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Superposition Principle
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Electric Field and Field Lines
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