The ground state of hydrogen has two closely-spaced energy levels, where oneelectron is spinning up and the other is spinning down. This energy transition corresponds to releasing excess energy as a photon at what wavelength?
A) 21 centimeters
B) 21 millimeters
C) 21 meters
D) 22.2 centimeters
E) 22.2 millimeters

Question

Quizplus · Accepted Answer

The 21-centimeter line corresponds to the wavelength of the photon released during the hyperfine transition of the ground state of hydrogen, where the spins of the electron and the proton flip from parallel to antiparallel (or vice versa), releasing a photon at this specific wavelength.

The Ground State of Hydrogen Has Two Closely-Spaced Energy Levels