Hi,(adsbygoogle = window.adsbygoogle || []).push({});

I am studying a section on mass flux and have come across the following integral over an arbitrary surface. I am told that the integral equals 4pi radians. Can someone direct me to a proof of this and explain why the denominator (r^{2}) drops out?

Thanks!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Integral over an arbitrary surface

**Physics Forums | Science Articles, Homework Help, Discussion**