# Wave interference

1. Nov 12, 2008

### kasse

If the amplitude of three intersecting waves is given by

$$y(r,t) = \frac{A}{r}e^{i(kr-wt)}[1-2cos(kdsin\theta)]$$

how can I then find the intensity at r = 200 m as a function of $$\theta$$?

I know that intensity is the square of the amplitude. Should I simply square y(r,t)? If I do, I get I as a function of t as well, because of the part $$e^{i(kr-wt)}$$.

2. Nov 12, 2008

### stunner5000pt

intensity is $$I=A^* A$$
where A is the amplitude
so that makes the exponential term go away

3. Nov 12, 2008

Thanks!