### Calculating number of photons emitted

Posted:

**Thu Oct 25, 2018 9:30 pm**Using the Einstein equation, how do you calculate the number of photons emitted from a light source??

Thanks!

Thanks!

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=15&t=34842

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Posted: **Thu Oct 25, 2018 9:30 pm**

Using the Einstein equation, how do you calculate the number of photons emitted from a light source??

Thanks!

Thanks!

Posted: **Thu Oct 25, 2018 9:50 pm**

The Einstein equation actually calculates the energy of a photon of light. Knowing that, you would use the total amount of energy that the light emits, divide this energy with the energy per photon, and calculate the number of photons.

Posted: **Sun Oct 28, 2018 11:29 pm**

The Einstein equation only accounts for the energy of a single photon of light, so if you had no other information, you wouldn't really be able to answer the equation. All you need to find the total number of photons is the total energy of the light source. You take the total energy and divide that with the energy value you calculated with the Einstein equation. That should give you the total number of photons from the light source.

Posted: **Fri Nov 02, 2018 10:33 am**

E = hv is energy for one photon. You need to be given total energy of light source in order to find number of photons. Divide the total energy of light by the energy per photon to find number of photons. Remember number of photons determines intensity of light, not energy per photon.