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Can electron spin change? If so how does this happen?
When people talk about spin then may mean two different things. One is the absolute value of spin (the length of the vector). For the electron this value is [tex] \hbar/2[/tex], and it never changes, i.e., this is a fixed property of the electron, like its mass or charge.Can electron spin change? If so how does this happen?
So the magnitude of the vector doesn't change but it's components do in a conservative way so as to keep a constant spin magnitude of h/4pi.When people talk about spin then may mean two different things. One is the absolute value of spin (the length of the vector). For the electron this value is [tex] \hbar/2[/tex], and it never changes, i.e., this is a fixed property of the electron, like its mass or charge.
Another thing is spin projection on a given axis (a vector component). This projection may be either [tex] +\hbar/2[/tex] or [tex] -\hbar/2[/tex], with probability weight assigned to each value. These probabilities may change in electron interactions, collisions, etc.
That's right.So the magnitude of the vector doesn't change but it's components do in a conservative way so as to keep a constant spin magnitude of h/4pi.
Pure physicists may not be aware of it, but the only real practical manifestation of spins is exposed by applying some equivalent of an external magnetic field to the device.Grampa, for heaven's sake, please turn your fount of misinformation down a notch.
First, as I said before, it is incorrect to describe a single electron as paramagnetic or diamagnetic. These are properties of bulk materials, not individual electrons. Second, the only person discussing applied magnetic fields is you. Third, the terms describing the orientation of spins with respect to external fields is not para- and dia-, but rather para- and ortho-.
Great answer and insight.When people talk about spin then may mean two different things. One is the absolute value of spin (the length of the vector). For the electron this value is [tex] \hbar/2[/tex], and it never changes, i.e., this is a fixed property of the electron, like its mass or charge.
Another thing is spin projection on a given axis (a vector component). This projection may be either [tex] +\hbar/2[/tex] or [tex] -\hbar/2[/tex], with probability weight assigned to each value. These probabilities may change in electron interactions, collisions, etc.
Isn't it [itex]\sqrt{3}\hbar/2[/itex]? It's actually in an eigenstate of S2, right?One is the absolute value of spin (the length of the vector). For the electron this value is [tex] \hbar/2[/tex], and it never changes, i.e., this is a fixed property of the electron, like its mass or charge.
No, the "z-component" (actually the component along any direction) of the spin angular momentum vector has that value (either + or -).No, the electron's spin is [itex]\frac{\hbar}{2}[/itex]
Don't forget to multiply by [itex]\hbar[/itex] if you're talking about the physical quantity (angular momentum) and not the quantum number.3/2, 1/2, -1/2, -3/2