Determine the de Broglie wavelength of a proton traveling at the speed of light and identify the region in the electromagnetic spectrum for this wavelength.

• A. λ = 2.48 × 10² m; radio waves
• B. λ = 7.55 × 10^–7 m; visible light
• C. λ = 4.91 × 10^–10 m; x-rays
• D. λ = 1.32 × 10^–15 m; gamma rays

Answer: (D)