Displacement current: I_d = ε₀ dΦ_E/dt

Ampere‑Maxwell law: ∮ B·dl = μ₀(I_c + I_d)

Maxwell's equations unified electricity, magnetism, and light.

Speed in vacuum: c = 1/√(μ₀ε₀) ≈ 3×10⁸ m/s

Relation: E₀ = c B₀ (amplitudes are related)

Energy density: u = ½ ε₀ E² + ½ B²/μ₀ = ε₀ E² (since B = E/c)

Energy density: u = ε₀ E² = B²/μ₀

Intensity (power/area): I = u c = ε₀ E² c = (E₀²)/(2μ₀ c) (for sinusoidal)

Poynting vector: S = (1/μ₀) E × B (direction of propagation)

Radiation pressure: P_rad = I/c (if fully absorbed), = 2I/c (if reflected).

Momentum: p = U/c (for photon)

💡 NEET TIPS & SHORTCUTS

• For EM wave, E and B are in phase; the wave is transverse.
• Speed in a medium: v = c/n, where n = √(μ_rε_r) ≈ √(ε_r) for non‑magnetic.
• Displacement current is essential for continuity of current in capacitor circuits.
• Order of EM spectrum: remember "Rabbits Mate In Very Unusual eXpensive Gardens" (Radio, Micro, IR, Visible, UV, X‑rays, Gamma).

⚠️ COMMON MISTAKES

• Confusing direction of E and B fields in propagation.
• Forgetting that displacement current exists even in vacuum (no actual charge flow).
• Using c = 3×10⁸ m/s in medium without considering refractive index.
• Assuming EM waves require medium – they don't (can travel in vacuum).

c = 1/√(μ₀ε₀) ≈ 3×10⁸ m/s

E₀ = c B₀

Displacement current: I_d = ε₀ dΦ_E/dt

Intensity: I = ½ ε₀ c E₀²

Poynting vector: S = (E × B)/μ₀

Radiation pressure: P = I/c (absorbed), 2I/c (reflected)