Practice question

**Hertz experiment** produced radio waves using spark gap LC oscillator, detected with loop antenna, confirming Maxwell's prediction, frequency ≈10⁸ Hz, wavelength ≈3 m, demonstrating EM waves travel at c, transverse, can be reflected, refracted, polarized. Microwaves are tuned to the resonant frequency of water molecules, causing them to oscillate and generate heat via friction, whereas infrared waves primarily heat surfaces through absorption. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Resonance with water molecules, illustrating EM wave transverse nature and Maxwell's displacement current concept.