Wavefunction normalisation and expectation values

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Homework Help Overview

The discussion revolves around the normalization of wavefunctions and the calculation of expectation values in quantum mechanics. Participants are examining the position and momentum expectation values, as well as the implications of their calculations.

Discussion Character

  • Exploratory, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to verify their calculations related to the position expectation value and expresses concern about proceeding with potentially incorrect foundations. Some participants question the correctness of the expressions for the momentum expectation value, noting issues with units and integration.

Discussion Status

Participants are actively engaging with the problem, providing feedback on each other's calculations. Some guidance has been offered regarding the use of LaTeX and considerations for complex numbers in expectation values. There is an ongoing exploration of different interpretations and approaches without a clear consensus.

Contextual Notes

There is mention of a preference for using images over text for equations, which may limit the clarity of the discussion. Additionally, the original poster is specifically focused on the position expectation value before proceeding further.

MoAli
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Homework Statement


See Image, Sorry Its easier for me to attach images than writing all equation on the forum's keyboard!
Screen Shot 2016-12-11 at 15.53.06.png
I only need to check if I'm working it out correctly up to the position expectation value because I don't want to dive in the rest on wrong basis !

Homework Equations


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The Attempt at a Solution


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You need to try some latex. What you have is correct, except that right at the end in the expected value of ##x##, ##\alpha## leapt from the denominator to the numerator.

##\langle x \rangle = \frac{12}{13 \alpha}##
 
Yeah still trying to learn latex, anyway, where the question asks to prove momentum expectation value is zero without integrals I get stuck, I got <p^2> = \frac{12/h^2}{13 } which still doesn't make sense to me, the units don't work!
 
MoAli said:
Yeah still trying to learn latex, anyway, where the question asks to prove momentum expectation value is zero without integrals I get stuck, I got the \langle p^2 \rangle to be \frac{12h^2}{72}

Regarding ##\langle p \rangle## you might like to think about complex numbers and expectation values.

I haven't tried to calculate ##\langle p^2 \rangle## or ##\langle x^2 \rangle##. You just need to be careful with the integration.
 

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