## Work Function and Energy of Photons

Racquel Fox 3L
Posts: 35
Joined: Wed Sep 30, 2020 10:11 pm

### Work Function and Energy of Photons

In some practice problems I've been doing I noticed that E=hv is equal to the work function. How do you know when you are supposed to set them equal to each other?

Rich Luong 1B
Posts: 38
Joined: Wed Sep 30, 2020 9:49 pm

### Re: Work Function and Energy of Photons

Usually when the question states, "the energy needed is equal to the work function," or "the kinetic energy of the electron is equal to zero" is when you'd use the equation for the work function.

Mohamed Mido
Posts: 52
Joined: Wed Sep 30, 2020 9:33 pm

### Re: Work Function and Energy of Photons

You set them equal to each other because the energy per photon must at least be equal to the work function for the electrons to be removed from the surface of the metal.

Sami Siddiqui 3L
Posts: 74
Joined: Wed Sep 30, 2020 9:58 pm
Been upvoted: 3 times

### Re: Work Function and Energy of Photons

We normally set hv equal to the work function under the circumstances he specified because of the law of conservation of energy. To say this in a form simpler than the equation we use for these cases, think of it this way:

energy of incoming photon = energy needed to release electron (work function) + kinetic energy

If the kinetic energy is 0, then we would just set hv equal to the work function. In doing so, we find the maximum wavelength that can remove an electron from a given metallic surface.

haileyk
Posts: 40
Joined: Wed Sep 30, 2020 10:03 pm

### Re: Work Function and Energy of Photons

Hi!

If the kinetic energy is equal to 0, you would set hv equal to the work function. This is because in order to remove an electron from the surface, the energy of the photon must be at least equal to or greater to the work function.