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. Using v λ = c , we have v = (c/λ) = (3 × 10⁸/8) = 3.75 × 10⁷ Hz . Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields 3.75 × 10⁷ Hz, illustrating EM wave transverse nature and Maxwell's displacement current concept.