Practice question

**Radio waves** λ≈10⁻¹ to 10⁴ m, f≈10⁴ to 10⁹ Hz, produced by rapid acceleration/deceleration of electrons in aerials/antenna, used for long-distance communication because low frequency diffracts around obstacles and reflects from ionosphere, enabling ground wave and sky wave propagation, effective for broadcasting. The Ampere-Maxwell law relates the magnetic field to both the conduction current and the displacement current, given by oint B · d l = μ₀ i_c + μ₀ ε₀ (d Φ_E/dt) . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Magnetic field to conduction and displacement currents, illustrating EM wave transverse nature and Maxwell's displacement current concept.