# Photons and the Photoelectric effect

• MrDMD83
In summary, the conversation discusses the calculation of wavelength of light incident on the surface of metallic sodium, given the work function and maximum speed of emitted photoelectrons. The relationship between frequency and wavelength of light is also mentioned, along with the formula for calculating kinetic energy. By dividing the sum of kinetic energy and work function by Planck's Constant and dividing the speed of light by frequency, the wavelength of the light can be determined.

## Homework Statement

Light is incident on the surface of metallic sodium, whose work function is 2.3 eV. The maximum speed of the photoelectrons emitted by the surface is 1.08 106 m/s. What is the wavelength of the light?

e=hf

p=h/wavelength

## The Attempt at a Solution

None so far

What is the kinetic energy imparted to the electron and thus what was the total energy of the photon.

Could you be a bit more specific?

Well you know the photon energy is the energy needed to remove the electron plus the kinetic energy of the emited electron. You are given the work function (i.e. the energy required to remove the electron) and the electron speed from which you can work out the kinetic energy of the electron. You have already stated the relation between photon energy and frequency. What is the relationship between frequency and wavelength of light?

So I use .5mv^2 to get the KE.
From there I divide the sum of the KE and work function by Planck's Constant. I then divide c by f to get the wavelength?

Ok, I got it. I made the problem more difficult than it needed to be. Thank you for the help.