Practice question

**X-rays in medicine** treat certain cancers because high-energy photons ionize and damage DNA of malignant cells, also imaging because bones absorb more than tissue, contrast. Gamma rays from Co-60 used for radiotherapy, energy ≈1.17 and 1.33 MeV, highly penetrating. The wave number k = (2 π/λ) . Given λ = 3 m , k = (2 π/3) ≈ 2.09 rad/m . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields 2.09 rad/m, illustrating EM wave transverse nature and Maxwell's displacement current concept.