Wave length measures the width of the wave
The ground<span> state of an electron, the energy level it normally occupies, is the state of lowest energy for that electron. ... An electron </span>can become excited<span> if it is given extra energy, such as if it absorbs a photon, or packet of light, or collides with a nearby </span>atom<span> or particle. (I do not take credit for that answer)</span>
