Is the photon energy formula E=hf an axiom?

[AyoubEd]

please look at he underligned formula. is it a axiom we have to ake for granted ?

 

[Drakkith]

No, we can and have measured this as far as I know.

 

[AyoubEd]

I think i got it
E=h.v
-De broglie : p=h/(the wace longitude:L)
hence:
E=h.c/L=p.c

 

[jtbell]

For relativistic particles, the general relationship between energy, momentum and mass is $$E = \sqrt {(pc)^2 + (mc^2)^2}$$ where m is the invariant mass (often called the "rest mass"). For photons, m = 0 which leads to E = pc.

 

[AyoubEd]

thanks a lot @jtbell