Re: [Phys-L] superposition and interference

["John Clement" <clement@hal-pc.org>]

There is a difference in usage.  One sees the terms "constructive
interference" or "destructive interference", but I have never seen
"constructive superposition".  I would say the terms have idiomatic
differences in usage although they refer to the same thing.  I suspect that
interference has more meaning to students than superposition.  Another
example might be "interference fringes" while "superposition fringes" would
never be used.  Interference by itself can also conjure up the idea of
cancellation, while superposition is more neutral on the subject.

The idea that interference is what you observe, but superposition is what is
going on might be part of the distinction.  One can talk about interference
of two wave pulses.  Superposition might just refer to the math.

John M. Clement
Houston, TX 

> When discussing waves in introductory university physics is 
> there an important distinction to be made between the terms 
> "superposition" and "interference?"
>
> It seems to me that superposition is a principle concept and 
> interference is a descriptor of the phenomenon when 
> superposition happens, but there's not a big reason to draw 
> any kind of "line" between the two.  Waves superpose; waves interfere.
>
> Maybe superposition is the more general of the two terms and 
> is something which is always happening. Would one reserve 
> "interference" to a pseudo-steady-state behavior that we see 
> in double-slits, diffraction gratings, and standing waves?