What Do Wave Crests in Electromagnetic Radiation Represent?

[land_of_ice]

On Wikipedia and in the textbooks, it is very general and it does not explain so, curious,
for the different wavelengths of radiation, (or light) what do the wave crests actually correspond to?
Do they correspond to the electron making a complete orbit around the nucleus, or to something else?
For instance, a particular type of wave is at a frequency of about 2.4×1023 Hz
is that how frequent the electron orbits around the nucleus and makes 1 rotation around it ?
Or is that because the electron is going from a higher to lower shell?

 

[pallidin]

Or is that because the electron is going from a higher to lower shell?

Yes.

 

[dulrich]

The dropping of the electron into the lower shell is where the energy for the radiation is coming from. But the crests are representing the amplitude of the wave. Since this is electromagnetic radiation, the crests correspond to the maximum electric and magnetic forces that would be felt by a charge if one were there at that particular moment in time.

And, you really shouldn't have the idea of the electrons as literally orbiting the nucleus. That is the old Bohr model. I like to think more of the electron as kind of resonating in a circular (read: spherical) pattern around the nucleus, somewhat like a bell. All of these pictures are inaccurate, but -- for me -- this idea is less so.