### units for energy

Posted:

**Wed Dec 04, 2019 8:23 pm**What are the units for energy in the E=hv equation? Is it Joules or Joules/photon?

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=15&t=54538

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Posted: **Wed Dec 04, 2019 8:23 pm**

What are the units for energy in the E=hv equation? Is it Joules or Joules/photon?

Posted: **Wed Dec 04, 2019 8:47 pm**

The unit is J, but in the E=hv equation you are finding the energy of a photon, so technically this value means the amount of energy per photon. I think you can just write J in your answer though.

Posted: **Thu Dec 05, 2019 2:23 pm**

The unit for energy is Joules, which is equivalent to a Newton*meter. Planck's constant h is in the units of m^{2}kgs^{-1} and the unit for v frequency v is s^{-1}. Multiplying these together you would get m^{2}kgs^{-2}. As a newton is in the units of kgms^{-2}, you can see that this equation indeed does find Joules, or N*m.