1. The problem statement, all variables and given/known data Flat harmonic electromagnetic wave propagates in the positive direction in vacuo axis y. Vector electromagnetic energy flux density is given by: S(y,t)=Sm *cos(wt-ky)2.Wave value: k=(2*π)/λ=0.41 m-1,Amplitude Sm=26 W/m2.Compare this wave with another wave. 2. Relevant equations ƒ=V/λ k=(2*π)/λ E=h*ƒ 3. The attempt at a solution I find wavelenght from wave value λ=15m ⇒ it is a radio short wave ⇒next i find frequency from ƒ=V/λ=2*107⇒and finally i find photon energy E=h*ƒ=1,3*10-26 J =81*10-9neV. I compared the result with the table, and he enters the period of short radio waves, ie, this wave is the same radio signal from your phone or radio?Maybe I made a mistake somewhere?