Electromagnetic Waves

📋 Course Outline

1. Maxwell’s Electromagnetic Unification
2. Displacement Current
3. Ampere–Maxwell Law
4. Sources of Electromagnetic Waves
5. Structure of Electromagnetic Waves
6. Wave Speed and Energy
7. Electromagnetic Spectrum
8. Applications of Spectrum Regions

📖 1. Maxwell’s Electromagnetic Unification

★ Must-know

• James Clerk Maxwell (1831–1879) showed that a time-varying electric field generates a magnetic field, completing the symmetry with Faraday’s result that a time-varying magnetic field generates an electric field.

• Maxwell’s equations, together with the Lorentz force formula, express the basic laws of electromagnetism and predict electromagnetic waves as coupled time-varying electric and magnetic fields propagating through space. — James Clerk Maxwell

• The predicted speed of electromagnetic waves was close to $3 \times 10^8\ \mathrm{m\,s^{-1}}$, the measured speed of light, leading to the conclusion that light is an electromagnetic wave. — James Clerk Maxwell

Further detail

• Hertz experimentally demonstrated electromagnetic waves in 1885, and their technological use by Marconi and others led to modern communication.

💡 Memory Hook