PhysicsExamsPrep.Con
Master Electrostatic Potential and Capacitance with 100+ MCQs for potential energy, capacitors, dielectrics, and energy storage.
Quick Revision: Electric Charges and Field
- Charge Quantization: Q = ±ne, where n is an integer and e = 1.6 × 10⁻¹⁹ C.
- Charge Conservation: Total charge in an isolated system remains constant.
- Coulomb's Law: F = (1/(4πε₀)) × (q₁q₂/r²); electrostatic force between two point charges.
- Electric Field (E): E = F/q₀; force per unit positive test charge. Vector quantity with SI unit N/C.
- Electric Field due to Point Charge: E = (1/(4πε₀)) × (q/r²) along radial direction.
- Electric Dipole Moment (p): p = q × 2a (magnitude); direction from -q to +q.
- Torque on Dipole: τ = pE sinθ in uniform electric field.
- Gauss's Law: Φ = ∮E·dA = Q_enclosed/ε₀; relates electric flux to enclosed charge.
- Electric Flux: Φ = E·A = EA cosθ; number of field lines passing through a surface.
- Field due to Infinite Line Charge: E = λ/(2πε₀r) ∝ 1/r.
- Field due to Infinite Sheet: E = σ/(2ε₀); constant and perpendicular to sheet.
- Field inside Conductor: Zero in electrostatic equilibrium.
- Permittivity of Free Space: ε₀ = 8.85 × 10⁻¹² C²/N·m².
- Electrostatic Constant: 1/(4πε₀) = 9 × 10⁹ N·m²/C².
Chapter Summary:
Electrostatic Potential and Capacitance extends the concepts from electric fields to potential energy and storage of electric charge. The chapter introduces electrostatic potential as a scalar quantity that represents the work done per unit charge, providing an alternative perspective to electric fields for analyzing electrostatic systems.
Key topics include the calculation of potential due to various charge distributions, the relationship between electric field and potential through gradient operations, and the concept of equipotential surfaces. The behavior of conductors and the principle of electrostatic shielding are explained through potential concepts. The chapter then transitions to capacitance, defining it as the ability of a conductor to store charge per unit potential.
Various capacitor configurations - parallel plate, spherical, and cylindrical - are analyzed with their respective capacitance formulas. Circuit applications cover series and parallel combinations of capacitors and the energy storage capabilities of these devices. The chapter concludes with the study of dielectrics, their polarization effects, and how they enhance capacitance while reducing the effective electric field within capacitors.
This chapter bridges the gap between fundamental electrostatics and practical electrical components, laying the groundwork for understanding more complex circuits and electromagnetic systems.
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