1. Apr 21, 2012

### kapitan90

1. The problem statement, all variables and given/known data
Hello,
I have problems with expressing a reflected wave mathematically.
In my printed notes I found the following formulas for reflected waves:
a) For a fixed end: incoming wave: $$y_1(x,t)=e^{-i(kx+ωt)}$$
reflected wave: $$y_2(x,t)=re^{i(kx-ωt)}$$ where r is the reflection coefficient.
I understand the - in front of ωt is because the wave has changed its direction, and the - in front of the whole power (before i) is because the wave is reflected.
Now for a free end: $$y_1(x,t)=e^{i(kx-ωt)}$$ it is said that $$y_2(x,t)=re^{i(-kx-ωt)}$$
2. Relevant equations
Shouldn't the reflected wave for a free end in this case be:
$$y_2(x,t)=re^{i(kx+ωt)}$$ because the wave is not inverted, but it changes its direction?

Any help appreciated!

Last edited: Apr 21, 2012
2. Apr 22, 2012

### kapitan90

Could anyone please have a look at this problem? I thought it was quite straightforward :(