Charge, field, and the dance of light.

Electromagnetism

Maxwell unified electricity, magnetism, and light into one elegant framework. Fields fill space, push charges, and travel as electromagnetic waves.

Signature∇·E = ρ/ε₀

Chapter outline

Lessons in this chapter

Short, focused lessons. Each one ends with a worked example and a quick quiz.

Key concepts at a glance

The essential ideas, paired with their equations.

Coulomb's Law

01
F = k·q₁q₂/r²

Force between two point charges.

Gauss's Law

02
∮E·dA = Q/ε₀

Electric flux through a closed surface equals enclosed charge.

Faraday's Law

03
ε = −dΦ_B/dt

A changing magnetic flux induces an EMF — the principle behind generators.

Ampère–Maxwell

04
∮B·dl = μ₀(I + ε₀ dΦ_E/dt)

Currents and changing electric fields create magnetic fields.

Lorentz Force

05
F = q(E + v×B)

Total electromagnetic force on a moving charge.

Maxwell's Equations

06

Four equations that fully describe classical electromagnetism and predict light.

Frequently asked

What is an electromagnetic field?+

A region of space where electric and magnetic forces act on charges, described jointly by Maxwell's equations.

Is light an electromagnetic wave?+

Yes — light is a self-propagating oscillation of electric and magnetic fields at speed c.

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