# Cylindrical wavefront

1. Jan 27, 2008

### dibiz116

does anyone know why, in order to conserve flux, the amplitude of a cylindrical wave varies inversely with its radius?

I know the equation for a cylindrical wave is $$\frac{A}{\rho^{1/2}}e^{i(k\rho\pm\omega t)}$$ , but how does this relate to conserving the flux?

The main reason for my question is that I do not know which flux this is referring to, the question only says "flux" and no type of flux is referred to in the chapter I'm working on.

So .. what type of flux is conserved because of a cylindrical waves' amplitude's inverse proportionality with the square root of the radius?

Thanks so much if anyone knows what I'm talking about.