Introductory QM boundary conditions

Click For Summary
The discussion revolves around finding the normalization constant C for a given wave function defined in different regions. Participants emphasize that the wave function must be continuous at the boundaries, specifically at -L/2, 0, and L/2, but initially conclude that C=0, which is not a valid solution. The normalization condition requires that the total probability of finding the particle equals 1, leading to the realization that C cannot simply be zero. Clarifications suggest that instead of checking continuity alone, the normalization integral should be used to determine C. Ultimately, the participants express that they have gained clarity on the correct approach to find C.
stephen8686
Messages
42
Reaction score
5

Homework Statement


A particle is represented by the following wave function:
ψ(x)=0 x<-L/2
=C(2x/L+1) -L/2<x<0
=C(-2x/L+1) 0<x<+L/2
=0 x>+L/2

use the normalization condition to find C

Homework Equations


ψ(x) must be continuous[/B]

The Attempt at a Solution


I'm supposed to say that at the points -L/2, 0, +L/2 ψ(x) must be continuous, so then I can find C. But I get C=0. For example at x= L/2 I get 0=0 and 0= -2C/L for the conditions so C=0.
I feel like I must just either overlooking something stupid or I'm just doing this completely wrong.
 
Physics news on Phys.org
stephen8686 said:
1But I get C=0. For example at x= L/2 I get 0=0 and 0= -2C/L for the conditions so C=0.
I feel like I must just either overlooking something stupid or I'm just doing this completely wrong.
At x = L/2 you get 0 = 0 no matter what the value of C. So, this doesn't help you determine C.

Find C by using the idea that the probability must equal 1 for finding the particle somewhere between x = -∞ and x = +∞.
 
  • Like
Likes stephen8686
TSny said:
At x = L/2 you get 0 = 0 no matter what the value of C. So, this doesn't help you determine C.

Find C by using the idea that the probability must equal 1 for finding the particle somewhere between x = -∞ and x = +∞.

Thanks TSny, I think I got it now
 
At first, I derived that: $$\nabla \frac 1{\mu}=-\frac 1{{\mu}^3}\left((1-\beta^2)+\frac{\dot{\vec\beta}\cdot\vec R}c\right)\vec R$$ (dot means differentiation with respect to ##t'##). I assume this result is true because it gives valid result for magnetic field. To find electric field one should also derive partial derivative of ##\vec A## with respect to ##t##. I've used chain rule, substituted ##\vec A## and used derivative of product formula. $$\frac {\partial \vec A}{\partial t}=\frac...