## Number of photons

sonalivij
Posts: 70
Joined: Fri Sep 28, 2018 12:27 am

### Number of photons

How do you use E=hv to calculate the number of photons emitted from a light source?

Vikramjeet Gill 1C
Posts: 30
Joined: Fri Sep 28, 2018 12:15 am

### Re: Number of photons

To the best of my knowledge I don't believe you could calculate the number of photons emitted in a light source with that equation but you could calculate the energy each photon holds. You would need to be given the number of photons for example if a problem said 4.99x10^-19J/mole all you would have to do is divide the energy by avagadros number to get the amount of energy each photon has.

Joonsoo Kim 4L
Posts: 61
Joined: Fri Sep 28, 2018 12:29 am

### Re: Number of photons

the "E" in E=hv is the energy per photon, so if a question asks how many photons a light source has, as long as the question gives you (or gives you a way to find) the frequency and total energy of the light, you can use E=hv to find the energy per photon, and then divide Etotal/Eper photon to get the number of photons.

ariellasarkissian_3H
Posts: 46
Joined: Fri Sep 28, 2018 12:25 am

### Re: Number of photons

You divide the total energy by the energy per photon to get the number of photons.

Kelly Hollman
Posts: 33
Joined: Fri Sep 28, 2018 12:27 am

### Re: Number of photons

You can use dimensional analysis! The total energy multiplied by 1 photon / energy (obtained from E = hv)

Ana Pedreros
Posts: 62
Joined: Fri Sep 28, 2018 12:19 am

### Re: Number of photons

Would the number of photons affect the amount of energy produced at a certain wavelength?

sonalivij
Posts: 70
Joined: Fri Sep 28, 2018 12:27 am

### Re: Number of photons

No, the number of photons would not affect the energy. The only thing the number of photons would affect is the intensity of the light.

KHuang1L
Posts: 60
Joined: Fri Sep 28, 2018 12:19 am

### Re: Number of photons

E = hv gives you the energy per photon. If the question gives you the total amount of energy, then you can divide that by E to get the number of photons.