Quantum mechanics - finite square well

AI Thread Summary
The discussion focuses on the relationship between transmission (T), reflection (R), and the parameters of a finite square well in quantum mechanics. It highlights confusion regarding how the width and height of the potential well affect T and R, specifically questioning the role of the wave number (k) in these calculations. The formulas for T and R are reiterated, emphasizing their dependence on k, which is derived from the potential energy and the particle's energy. Clarification is sought on the definitions and applications of k in the context of these formulas. Understanding these relationships is crucial for accurately predicting particle behavior in quantum wells.
Graham87
Messages
72
Reaction score
16
Homework Statement
In which case would you expect the reflection coefficient to largest, for a particle with energy E?

For which of the energy levels would you expect that the tansmission coefficient would be largest?
Relevant Equations
##R=\frac{|A|^2}{|B|^2}##

##T=1-R##

##k=\sqrt{\frac{2m(V_0-E)}{h}}##

##\psi(x)=Ae^{kx}+Be^{-kx}##
5B8339D6-25BE-4C8D-8B2F-C3F02DEAF4B3.jpeg

In a) I get that T should be largest where V_0 is least wide, because when V_0 is infinitely wide the particle would be fully reflected.
But I don't get how height in b) and energy levels height in c) correlates to T and R.

Is it because of their k? I get the opposite answer from the correct one when I plug k in the R formula. ##R=\frac{|A|^2}{|B|^2}##

##T=1-R##

##k=\sqrt{\frac{2m(V_0-E)}{h}}##

##\psi(x)=Ae^{kx}+Be^{-kx}##Thanks!
 
Last edited:
Physics news on Phys.org
Graham87 said:
But I don't get how height in b) and energy levels height in c) correlates to T and R.

Is it because of their k? I get the opposite answer from the correct one when I plug k in the R formula.
You need to define what you mean by ##k##. And what formulas are you using for ##T## and ##R##?
 
vela said:
You need to define what you mean by ##k##. And what formulas are you using for ##T## and ##R##?
Done!
 
Thread 'Help with Time-Independent Perturbation Theory "Good" States Proof'
(Disclaimer: this is not a HW question. I am self-studying, and this felt like the type of question I've seen in this forum. If there is somewhere better for me to share this doubt, please let me know and I'll transfer it right away.) I am currently reviewing Chapter 7 of Introduction to QM by Griffiths. I have been stuck for an hour or so trying to understand the last paragraph of this proof (pls check the attached file). It claims that we can express Ψ_{γ}(0) as a linear combination of...
Back
Top