# What is this equation

1. Sep 20, 2009

### ATPenergy

What is this equation I$$\gamma$$=($$\Gamma$$N)/D2

It is about Intensity of ray.
But I can't find any information about it.
What is it? And where can I get the information?

2. Sep 20, 2009

### tiny-tim

Hi ATPenergy!
I'm not sure, but it looks a bit like irradiance = radiant flux (or radiant power) per area

what book did you get it from?

Last edited by a moderator: May 4, 2017
3. Sep 21, 2009

### Rajini

Hi,
i think it is the relation between natural line width, mean life time and Planck's constant!!!
the correct relation which i know (FWHM)*meanlifetime=hbar.