Practice question

**Aerials produce radio waves** by rapid acceleration/deceleration of electrons in antenna driven by AC, frequency equals driving frequency, for 60 MHz, λ=c/f=3×10⁸/60×10⁶=5 m, half-wave antenna length λ/2=2.5 m, efficient radiation when antenna size comparable to λ. Using E₀ = B₀ c , we have E₀ = (6 × 10⁻⁸) × (3 × 10⁸) = 18 V/m . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields 18 V/m, illustrating EM wave transverse nature and Maxwell's displacement current concept.