What is the shortest and least penetrating light of the electromagnetic spectrum?

• A. Infrared light
• B. Visible light
• C. Gamma rays
• D. Ultraviolet light

Answer: (D)

The main idea here is how wavelength relates to energy and how deeply light can penetrate matter. Shorter wavelengths carry more energy, and among these options the shortest wavelength is gamma rays. They are highly penetrating, able to pass through many materials. Ultraviolet light is indeed more energetic than visible and infrared, but its wavelength is longer than that of gamma rays, and it is largely absorbed by many substances and by the atmosphere, so it doesn’t penetrate as deeply as gamma rays. So the statement that ultraviolet is the shortest and least penetrating doesn’t align with how wavelength and penetration actually compare across these kinds of light; gamma rays are the shortest in wavelength and the most penetrating.