# Need help on probability amplitudes

1. Feb 4, 2005

### yizoink

I have this problem:

The total number of waves Nw in a box is somewhat uncertain beause of the way the amplitude falls off. For a region of size DeltaX, call the uncertainty in the number of waves DeltaNw.

a.) Relate DeltaNw to the uncertainty principle in the wavelength Delta(lambda). Assuming DeltaNw is about +/- 1, write this relation as an uncertainty principle relating DeltaX and Delta(Lambda).

I have no clue how to start this, but I do have this eqn from Feynman's lecture, which we're using.

Delta(lambda)/lambda = 1/(N*m)

where N = # of lines on the grating
m = order of diffraction pattern.

I don'tknow if this eqn. corresponds to this though.

so I'll assume...

Delta(lambda) = 1/(delta(Nw) ? Am I going about it the right way?

2. Feb 4, 2005

### Gokul43201

Staff Emeritus
Is this equation dimensionally consistent ?

Can you write out the given question exactly as it has been stated to you ? Are we talking about "matter waves" of a particle in some kind of potential box, or somthing else ?

Also, some background will be useful. What has been covered so far ?