What happens when the electron in a hydrogen atom flips its direction of spin, from parallel to anti parallel to that of the proton?
A) Nothing, this transition never occurs.
B) The atom emits 656-nm radiation that gives red color.
C) The atom emits high-energy ultraviolet rays.
D) The atom emits 21-cm radio radiation.

Question

Quizplus · Accepted Answer

When the electron in a hydrogen atom flips its spin from parallel to antiparallel to that of the proton, it undergoes a hyperfine transition, emitting 21-cm radio radiation, which is a key observation in radio astronomy.

What Happens When the Electron in a Hydrogen Atom Flips