What is the Normalisation Constant for an Electron in Spin State?

AI Thread Summary
The discussion focuses on determining the normalization constant A for an electron in the spin state represented by the vector (3i, 4). Participants clarify that the normalization constant is calculated to ensure the wave function integrates to unity. The calculation involves finding the magnitude of the vector, leading to the conclusion that A equals 1/5. Additionally, there is a brief explanation of the significance of spin states and normalization in quantum mechanics. The conversation concludes with a participant expressing clarity on the topic.
ZoroP
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Normalisation constant~ help~~

Homework Statement



An electron is in the spin state |> = A (3i, 4), so determine the normalisation constant A.

Homework Equations



:rolleyes: :frown:

The Attempt at a Solution



:cry: Well, I get confused about this questions, can anybody tell me what the normalisation constant is in this case? And does "in the spin state" mean something for given condition? Thanks a lot.
 
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ZoroP said:

Homework Statement



An electron is in the spin state |> = A (3i, 4), so determine the normalisation constant A.

Homework Equations



:rolleyes: :frown:

The Attempt at a Solution



:cry: Well, I get confused about this questions, can anybody tell me what the normalisation constant is in this case? And does "in the spin state" mean something for given condition? Thanks a lot.
Spin is simply a property that particles posses and this "spin state" describes, well the state of the spin of a particle or system of particles.

As for the question, what does one normally mean when one says a "normalisation constant". What does it mean in the context of a wave function for example?
 


Well, thanks a lot, but i don't think this problem is discussing about wave function, I cannot find any concept about wave function in my lecture notes. Thus, I consider that this question is only about math and calculation. Or maybe you can teach me some about the wave function or any other ideas? Thanks any way~
 


Do you know about complex vectors? And how to normalize those to unit length?
 


yes, o! you mean I can just do it like A = 1/|(3i, 4)|?? Thanks!
 


Yep, that's all there is to it. But don't forget to simplify that expression for A you got now.
 


Thanks, so it's A = 1/5
 


So in Physics we can write the spin state as a function of the particle:

|\psi \rangle = A \left ( \begin{array}{cc} 3i \\ 4 \end{array} \right)

But wave function must integrate to unity over all space, so:

\langle \psi | \psi \rangle = 1 = A^2\left ( \begin{array}{cc} -3i & 4 \end{array} \right) \left ( \begin{array}{cc} 3i \\ 4 \end{array} \right) = 25A^2

So I agree with your answer
 


BerryBoy said:
So in Physics we can write the spin state as a function of the particle:

|\psi \rangle = A \left ( \begin{array}{cc} 3i \\ 4 \end{array} \right)

But wave function must integrate to unity over all space, so:

\langle \psi | \psi \rangle = 1 = A^2\left ( \begin{array}{cc} -3i & 4 \end{array} \right) \left ( \begin{array}{cc} 3i \\ 4 \end{array} \right) = 25A^2

So I agree with your answer


I friggin get it now!
 
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