Re: Wave Question

[DEVARAKONDA VENKATA NARAYANA SARMA <narayana@HD1.DOT.NET.IN>]

At 08:42 AM 9/12/99 +0800, you wrote:
> > Perhaps we can also say that the intensity should always be calculated
> > from the resultant amplitude obtained by adding individual amplitudes
> > giving due consideration to the phase and not by adding individual
> > intensities.
> > Intensity should be always via amplitude.
> >
> > regards,
> >
> > sarma.
>
> Calculating from the amplitude is well-established. But I was pondering
> where the "extra" energy came from, and this has also been answered
> qualitatively --- by looking at the whole system, i.e. while the energy has
> doubled at constructive points, the energy is lowered on other points. But
> how do we prove it more convincingly, maybe mathematically?
>
> romanza

I think that is what is meant by adding amplitudes with consideration
for phase. You can treat them as vectors  with magnitude equal to the
amplitude and inclined at angles equal to their phase difference and add
them vectorially to obtain the resultant amplitude.

By the way, you mean the energy has quadrapled at constructive points.

regards,

sarma.