### Delta E values

Posted:

**Fri Oct 12, 2018 1:31 pm**For V=E/h, why do we use the a positive delta E value even though it is actually negative?

Created by Dr. Laurence Lavelle

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

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=15&t=33662

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Posted: **Fri Oct 12, 2018 1:31 pm**

For V=E/h, why do we use the a positive delta E value even though it is actually negative?

Posted: **Fri Oct 12, 2018 1:35 pm**

Yes, when the original calculation gives a negative value it just signifies that there was a negative change overall, but you can't have negative energy. The negative sign is just there for conceptual understanding.

Posted: **Fri Oct 12, 2018 2:09 pm**

For the equation E=hv, you're trying to calculate the energy of a photon. The energy of an emitted photon can never be negative, that just doesn't make sense. When we discuss a negative delta E we're talking about a loss of energy. That equation doesn't deal with energy change; the equation E=(-hR)/n^2 does. That's where a negative E is permitted, because when electrons lose energy their energy in essence becomes "more negative". I hope that helped!!