Electron vs Photon question? Significance of momentum?

[ehild]

Do the mirrors have a reflective index that tends towards one with increasing frequency?

Mirrors are made with highly reflecting materials, usually from metals, like gold or aluminium. Metals have high refractive index and high absorption, both changing with frequency, and above some frequency, they do not behave like metals any more.

 

[Let'sthink]

comparing wavelengths is one issue and comparing energies and momenta is another. comparison works fine for altogether different systems such as optical and electron microscopy instruments because mathematics is simpler and equivalent. Photons will not work in electron microscopy and electrons will not work in optical microscopy instruments.

Coming to the second issue, momentum and energy of two particles in non relativistic case and for particles with non-zero rest mass is simply:
P = √2mE and [E = (p^2)/2m]. The first equation tells us that the momentum of the heavier of the two particles having equal energy will be larger. and second equation tells us that the the energy of the heavier particle of the particles with same momentum will be smaller. I think such a comparison should not be made between photon and an electron.