Practice question

**Gamma rays** λ<10⁻² nm, f>10¹⁹ Hz, produced by nuclear transitions and radioactive decay, associated with nuclear processes because nuclear energy levels MeV vs atomic eV, highest photon energy, used in cancer treatment due to high penetration and cell damage, also sterilization, astronomy. Using v λ = c , we have λ = (c/v) = (3 × 10⁸/75 × 10⁶) = 4 m . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields 4 m, illustrating EM wave transverse nature and Maxwell's displacement current concept.