Electrostatics
Coulomb's law, electric field, potential, capacitors
Key Concepts
- Coulomb's law: force between point charges
- Electric field lines originate from positive, terminate at negative charges
- Electric potential: work done per unit charge to bring test charge from infinity
- Gauss's law: total flux through closed surface = Q_enclosed / ε₀
- Electric field inside a conductor is zero; potential is constant
Important Formulae
| Coulomb's force | F = kq₁q₂/r²; k = 9×10⁹ N·m²/C² |
| Electric field | E = kq/r² |
| Electric potential | V = kq/r |
| Capacitance (parallel plate) | C = ε₀A/d |
| Energy stored in capacitor | U = ½CV² = Q²/2C |
| Gauss's law | ∮E·dA = Q_enc/ε₀ |
Quick Tips
- Capacitors in series: 1/C_eff = Σ(1/Cᵢ); in parallel: C_eff = ΣCᵢ.
- Dipole: p = qd; torque τ = pE sinθ; potential energy U = −pE cosθ.
- Dielectric increases capacitance by factor κ (dielectric constant).
Sample Practice Questions
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Potential at the centre of a charged ring of radius R and charge Q:
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Answer: kQ/R
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Gauss's law states that total electric flux through a closed surface equals:
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Answer: Q_enclosed/ε₀
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Torque on an electric dipole of moment p in field E at angle θ:
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Answer: pE sinθ
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Electric field due to an infinite plane sheet of charge density σ:
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Answer: σ/2ε₀
Practice Questions
Practice 20 randomly selected NEET questions on Electrostatics. Answers are revealed after each question.
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What are the key concepts in Electrostatics for NEET?
Coulomb's law: force between point charges; Electric field lines originate from positive, terminate at negative charges; Electric potential: work done per unit charge to bring test charge from infinity; Gauss's law: total flux through closed surface = Q_enclosed / ε₀; Electric field inside a conductor is zero; potential is constant.
Which formulae are important for Electrostatics in NEET?
Coulomb's force: F = kq₁q₂/r²; k = 9×10⁹ N·m²/C²; Electric field: E = kq/r²; Electric potential: V = kq/r; Capacitance (parallel plate): C = ε₀A/d; Energy stored in capacitor: U = ½CV² = Q²/2C; Gauss's law: ∮E·dA = Q_enc/ε₀.
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