A particular photon of ultraviolet (UV) light has a wavelength of 200 nm and a photon of infrared (IR) light has a wavelength of 2000 nm. What is the energy of the UV photon compared to that of the IR photon?
A) The UV photon has 1/10 of the energy of the IR photon.
B) The UV photon has 10 times more energy than the IR photon.
C) The UV photon has 1/100 of the energy of the IR photon.
D) The UV photon has 100 times more energy than the IR photon.

Question

Quizplus · Accepted Answer

The energy of a photon is inversely proportional to its wavelength, according to the equation E = hc/λ, where E is energy, h is Planck's constant, c is the speed of light, and λ is the wavelength. Therefore, a photon with a shorter wavelength (like the UV photon at 200 nm) has more energy than a photon with a longer wavelength (like the IR photon at 2000 nm). Since the wavelength of the UV photon is 1/10th that of the IR photon, its energy is 10 times greater.

A Particular Photon of Ultraviolet (UV) Light Has a Wavelength