Question

The energy of microwaves is less than the energy of ultraviolet light. Which comparison of the energies of electromagnetic waves is correct?

X-rays have lower energy than gamma rays because X-rays have higher frequencies.
X-rays have lower energy than gamma rays because X-rays have shorter wavelengths.
Visible light has higher energy than infrared light because visible light has longer wavelengths.
Visible light has higher energy than infrared light because visible light has higher frequencies.

Answer 1

Correct: "Visible light has higher energy than infrared light because visible light has higher frequencies."

Reason: a photon’s energy E = h·f (h = Planck’s constant), so higher frequency (f) means higher energy. Frequency and wavelength are inversely related (f = c/λ), so shorter wavelength also means higher energy.