Two beams of light, a red beam and a blue beam, have the same energy. The beam with the greater number of photons is the
A) blue beam.
B) red beam.
C) both the same

Question

Quizplus · Accepted Answer

The energy of a photon is directly proportional to its frequency (E = hf, where h is Planck's constant and f is the frequency). Since blue light has a higher frequency than red light, each photon of blue light has more energy than a photon of red light. Therefore, for two beams of light to have the same total energy, the beam with the lower frequency (red light) must have more photons.

Two Beams of Light, a Red Beam and a Blue