Practice question

**Ultraviolet** λ≈10-400 nm, produced by atomic transitions and Sun, causes fluorescence, sterilization, harmful to eyes/skin, absorbed by ozone layer. **X-rays** λ≈10⁻² to 10 nm, produced by rapid deceleration of energetic electrons in X-ray tube, used in medicine for diagnosis (shadow of bones) and cancer therapy due to high ionization and penetration, detected by photographic film and Geiger counter. The document mentions that gamma rays are used in medicine to destroy cancer cells. Using c = fλ, E₀/B₀ = c, I_d = ε₀ dΦ_E/dt, and spectrum classification λ = c/f, evaluation yields Destroying cancer cells, illustrating EM wave transverse nature and Maxwell's displacement current concept.