posted by maggie .
Consider a single photon of red laser light, with wavelength of 633 nm (nano is 10-9).
What energy does this carry? What momentum? How does the energy compare to
typical atomic energies of a few times 10-19 J?
The energy is E = h*c/(wavelength)
The momentum is E/c = h/(wavelength)
h is Planck's constant, which you should know or look up. It has units of energy*time
The energy in a photon at that wavelength should be a few times 10^-19 J, or a few electron volts.