How is the energy-frequency relation for photons derived?

[Hepic]

E=h*f (h constant of Planck,f frequency)

What is the proof of that equation?

 

[f95toli]

It agress with experiments.
It is such a fundamental relation in physics that it is implicitly tested every day in lots of experiments and also a fair amount of engineering.

 

[Hepic]

Ok,thank you,but how scientist undestood that?
Also how Planck found this constant?

 

[jtbell]

Planck made the assumption that E = nhf while deriving an equation that fit experimental observations on black body radiation. A Google search for "planck black body radiation" finds many web pages that attempt to explain the details, for example

http://galileo.phys.virginia.edu/classes/252/black_body_radiation.html

 

[velo city]

https://www.youtube.com/watch?v=9DNpllmYP60&index=14&list=PL04722FAFB07E38E1

Watch this video about the ultraviolet catastrophe to get more info.

 

[Matterwave]

Ok,thank you,but how scientist undestood that?
Also how Planck found this constant?

Planck did not find the constant, he made an ansatz (an educated guess). He found that by making this ansatz, that there is some fundamental constant h and that the energy of a vibrational mode (of whatever is vibrating inside a black body) can only be in integer multiples of this constant times the frequency (nhf), he was able to solve the ultra-violet catastrophe. Subsequently, matching with experiment determined the numerical value of this constant.

 

[Hepic]

Thank you for your answers,everybody!