Question

Light with a wavelength of 5.0 · 10-7 m strikes a surface that requires 2.0 ev to eject an electron. Calculate the energy, in joules, of one incident photon at this frequency.

Answer 1

The appropriate equation to use is one from Max Planck:\[E=h \nu\]where E is the energy of a photon; h is Planck's constant; and ν is the photon's frequency. Of course you also know the following:\[\lambda \nu =c\]where λ is the photon's wavelength and c is the speed of light.

Once you're done you can compare to the energy required to eject a photon by realizing that 1eV=1.6022*10^-19 J. The problem doesn't ask for that, but it might pique your curiosity.