Electric Potential

This page focuses on electric potential and related concepts. It introduces the ideas of electric potential energy and potential difference.

Electric potential energy is given by U = kq₁q₂/r. The electric potential is defined as the potential energy per unit charge: V = U/q = kq/r.

Vocabulary: Potential difference is the work done per unit charge to move between two points in an electric field.

The potential difference in a uniform electric field is given by ΔV = Ed, where E is the field strength and d is the distance.

Example: To calculate the electric field strength from a potential difference, use E = ΔV/Δs, where Δs is the distance between points.

The page also covers the relationship between electric field and potential: E = -ΔV/Δs, with the field direction from higher to lower potential.

Highlight: The work done by the electric field is equal to the negative change in potential energy: W = -ΔU

Electrostatic Phenomena and Electric Current

This page covers capacitance, electric current, and Kirchhoff's laws. It provides formulas for calculating capacitance and current in various scenarios.

Capacitance is defined as the ratio of charge to potential difference: C = Q/V. For a parallel plate capacitor, C = ε₀A/d, where A is the plate area and d is the separation.

Definition: Kirchhoff's first law states that the sum of currents entering a node equals the sum of currents leaving it.

The page also introduces Ohm's law: V = IR, relating voltage, current, and resistance.

Highlight: Kirchhoff's second law states that the sum of potential differences around any closed loop in a circuit is zero.

The power dissipated in a resistor is given by P = I²R. For a power source, P = IV.

Vocabulary: Electromotive force (emf) is the energy supplied per unit charge by a power source.

The page concludes with a reminder of the principle of conservation of energy and its application to electrical systems.

Electric Field

This page covers fundamental concepts related to electric fields and Gauss's theorem. It provides key formulas for calculating electric field strength in various scenarios.

The electric field vector is defined as the force per unit charge: E = F/q. For a point charge, the electric field strength is given by E = kq/r^2, where k is Coulomb's constant.

Definition: Gauss's theorem states that the electric flux through a closed surface is proportional to the enclosed charge: Φ(E) = Q/ε₀

The page also covers electric fields for specific charge distributions:

• Infinite uniformly charged plane: E = σ/(2ε₀)
• Infinite linear charge distribution: E = λ/(2πε₀r)
• Spherical charge distribution (external): E = Q/(4πε₀r²)
• Homogeneous charged sphere (internal): E = Qr/(4πε₀R³)

Highlight: The electric field inside a conductor is zero in electrostatic equilibrium.