Which option has the shortest wavelength: microwave, X-rays, radio, ultraviolet light, or visible light?

Which option has the shortest wavelength: microwave, X-rays, radio, ultraviolet light, or visible light?

• A. X-Rays
• B. Microwave
• C. Radio
• D. Ultraviolet light

Answer: (A)

Wavelength is inversely related to energy and frequency, so the shorter the wavelength, the higher the energy of the photon. In the electromagnetic spectrum, radio waves have the longest wavelengths, microwaves are shorter, visible light is shorter still, ultraviolet is shorter than visible, and X-rays have the shortest wavelengths among these options. Rough ranges help see the pattern: radios are about meters to kilometers, microwaves millimeters to centimeters, visible light about 400–700 nanometers, ultraviolet roughly 10–400 nanometers, and X-rays around 0.01–10 nanometers. Since X-rays sit at the high-energy, short-wavelength end of the list, they have the shortest wavelength.