Understanding "Oscillators in Cavity Walls

[asdf1]

I'm reading a modern physics textbook, and have trouble understanding this sentence:
"Oscillators in the cavity walls can interchange energy with standing waves in the cavity only in quanta of hf"
What is meant by that?

 

[inha]

Are you perhaps reading about black body radiation and the UV catastrophe?

Check out hyperphysics for example. http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html#c1

 

[James R]

For "oscillators" read "atoms"; for "quanta" read "photons"; for "hf" read "energy hf, where f is the frequency".

 

[Antiphon]

It means that for a fixed frequency, the energy exchange may only occur
as integer multiples of hf, that is hf, 2hf, 3hf ...

Note: The "walls" means the electrons or atoms or molecules of the walls.
It could even mean other things. A quantum oscillator is anything that
can be excited into a state of definit energy (frequency) like the vibrational
states of a molecule.

 

[asdf1]

oh, i see~
thanks! :)