Which of the following photons carries the smallest amount of energy?

• A. A photon of ultraviolet light
• B. A photon of infrared light
• C. A photon of visible light
• D. A photon of X-ray radiation

Answer: (B)

Verified step by step guidance

1. Recall that the energy of a photon is directly proportional to its frequency and inversely proportional to its wavelength. The relationship is given by the equation: \(E = h \nu = \frac{h c}{\lambda}\), where \(E\) is energy, \(h\) is Planck's constant, \(\nu\) is frequency, \(c\) is the speed of light, and \(\lambda\) is wavelength.
2. Understand the electromagnetic spectrum order from highest to lowest energy: X-rays have the highest energy, followed by ultraviolet light, visible light, and infrared light having the lowest energy among these options.
3. Identify that since energy is inversely proportional to wavelength, photons with longer wavelengths carry less energy. Infrared light has a longer wavelength compared to ultraviolet, visible, and X-ray radiation.
4. Compare the given photon types by their typical wavelengths: X-rays (~0.01 to 10 nm), ultraviolet (~10 to 400 nm), visible (~400 to 700 nm), and infrared (~700 nm to 1 mm). Infrared photons have the longest wavelength and thus the smallest energy.
5. Conclude that among the options, the photon of infrared light carries the smallest amount of energy because it has the lowest frequency and longest wavelength.