Determine the energy of a photon in Ev, the wavelength of which is 500 nm.

We give all the values ​​from given in the SI system:
λ = 500 nm. = 500 * 10 ^ -9 m.
Let’s write down the Einstein equation:
h * ν = A + Tmax, where A is the work function of an electron from the metal, Tmax is the maximum kinetic energy of photoelectrons, h * ν is the energy of a photon.
E = h * ν, where h is Planck’s constant h = 6.63 * 10 ^ -34 J * s, ν is the radiation frequency.
The radiation frequency is found from the expression:
ν = c / λ, where c is the speed of light c = 3 * 10 ^ 8 m / s, λ is the wavelength.
Let’s substitute in the photon energy:
E = h * s / λ
Substitute the numerical values ​​and find the photon energy:
E = h * s / λ = 6.63 * 10 ^ -34 * 3 * 10 ^ 8/500 * 10 ^ -9 = 3.978 * 10 ^ -19 J.
Let’s translate into eV:
3.978 * 10 ^ -19 J / 1.6 * 10 ^ -19 = 2.48 eV.
Answer: the photon energy is 2.48 eV.