An atom that absorbs a photon of a certain energy can then emit
A)only a photon of that energy.
B)a photon of any energy.
C)only a photon of the same or higher energy.
D)only a photon of the same or lower energy.

Question

Quizplus · Accepted Answer

When an atom absorbs a photon, it moves to an excited state with higher energy. The atom can then return back to its ground state by releasing the excess energy as a photon. However, the emitted photon must have lower energy than the absorbed photon, otherwise it would violate the conservation of energy. Therefore, the atom can only emit a photon of the same or lower energy than the absorbed photon, which is option D.

An Atom That Absorbs a Photon of a Certain Energy