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Hi,

Is the energy a photon carries with respect to its frequency the same as that of its momentum energy? My understanding is that it is by the energy relations,

$$hf=E$$

$$E^2=p^2c^2+m^2c^4=p^2c^2$$ for a photon with ##m=0##, frequency ##f## and plank constant ##h## . So we have from both,

$$p=\frac{hf}{c}$$ Where ##p## and ##c## are the momentum of the photon and speed of light respectively.

The issue I have is with photon absorption, as an atom absorbs a photon of frequency ##f## and excites an electron to the next highest state, that state being ##hf## higher than the previous, then how does the photon also transfer momentum to the atom if all its energy is taken by the excitation of the electron?

Is the energy a photon carries with respect to its frequency the same as that of its momentum energy? My understanding is that it is by the energy relations,

$$hf=E$$

$$E^2=p^2c^2+m^2c^4=p^2c^2$$ for a photon with ##m=0##, frequency ##f## and plank constant ##h## . So we have from both,

$$p=\frac{hf}{c}$$ Where ##p## and ##c## are the momentum of the photon and speed of light respectively.

The issue I have is with photon absorption, as an atom absorbs a photon of frequency ##f## and excites an electron to the next highest state, that state being ##hf## higher than the previous, then how does the photon also transfer momentum to the atom if all its energy is taken by the excitation of the electron?

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