Practice question

**Momentum of EM wave** p = U/c, U energy, radiation pressure exerts force F = I A/c, small but measurable, comet tail pushed by sunlight, solar sail concept. For E₀=45 V/m, B₀=1.5×10⁻⁷ T, intensity I =0.5×3×10⁸×8.85×10⁻¹²×45²≈2.69 W/m². Gamma rays have very high energy and penetrating power due to their short wavelengths, allowing them to target and destroy cancer cells effectively. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields They destroy cancer cells, illustrating EM wave transverse nature and Maxwell's displacement current concept.