Generating LaserElectricity and Magnetism Level 2
a) Level \(2\) is a metastable state.
b) Electrons stay longer at \(E_2\) than at \(E_3\).
c) There is no electron that shows a spontaneous transition from \(E_2\) to \(E_1\).
d) If a laser beam can be generated constantly, the electron population in level \(2\) must be larger than the electron population in level \(1.\)