Re: superposition

[Leigh Palmer <palmer@SFU.CA>]

On 26-Feb-04, at 1:00 AM, RAUBER, JOEL wrote:

> A good non-linear example is intensity in interference and diffraction
> phenomena.
>
> Intensity at the central peak for two point sources:
>
> 1+1 = 4
>
> and of course the points of destructive interference provide the
> opposite
> case!
>
> I'm glad this came up, I follow an optics before E&M ordering, and we
> just
> started electric fields, it will be good to remind them of intensity
> being a
> "familiar" non-superposition situation.
>
> Joel R.

Arghh!

 In the first place I don't see why an example of some misapplication
of the principle of superposition is needed at all. Such
misapplications are surely uncountably numerous. No one mentioned Gin
Rummy, for example; superposition doesn't work there either, but so
what?

In the second place, I can't think of a worse example than "intensity
in interference and diffraction phenomena" being used as a
counterexample for which superposition does not work. Surely one incurs
the peril of making some of the duller students think that
superposition is inappropriately applied to interference phenomena.

Leigh