Proof of some identities regarding spin angular momentum.

In summary, the conversation discusses the definition of Si which is equal to 1/2 times the reduced Planck's constant multiplied by sigma. The question then asks what the result will be if sigma dot vector A is multiplied by sigma dot vector B. It is noted that sigma i is the Pauli matrix. The next question asks about the simplification of <Alpha|S|Alpha>, where S is the spin vector and |Alpha> is equal to "exp[{i*(S dot n_hat)*Theta/(reduced Planck's constant)}]". The conversation also suggests that the use of LaTex would make the discussion easier to understand.
  • #1
Faisal Moshiur
15
0
If we define Si=(1/2)× (reduced Planck's const)×sigma
Then what will be (sigma dot vect{A})multiplied by (Sigma dot vect{B})
Here (sigma)i is Pauli matrix.
Next one is, what will we get from simplifying
<Alpha|vect{S}|Alpha> where vect{S} is spin vector & |Apha>is equal to " exp[{i×(vect{S} dot (n_hat))× Theta/(reduced Planck's const)}]
 
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  • #2
Faisal Moshiur said:
If we define Si=(1/2)× (reduced Planck's const)×sigma
Then what will be (sigma dot vect{A})multiplied by (Sigma dot vect{B})
Here (sigma)i is Pauli matrix.
Next one is, what will we get from simplifying
<Alpha|vect{S}|Alpha> where vect{S} is spin vector & |Apha>is equal to " exp[{i×(vect{S} dot (n_hat))× Theta/(reduced Planck's const)}]

Well, first help your reader by learning how to use LaTex. This is very easy and we have a tutorial on this forum. Then what is "multiplied" ?
 
  • #3
dextercioby said:
Well, first help your reader by learning how to use LaTex. This is very easy and we have a tutorial on this forum.
Namely, here: https://www.physicsforums.com/help/latexhelp/

To start you off, the code S_i = \frac 1 2 \hbar \sigma enclosed in the appropriate delimiters (as described in the link above) produces $$S_i = \frac 1 2 \hbar \sigma$$ Is this what you intended to write for your first equation?
 

1. What is spin angular momentum?

Spin angular momentum is a property of particles, such as electrons, that describes their intrinsic angular momentum. It is one component of the total angular momentum of a particle.

2. How is spin angular momentum measured?

Spin angular momentum is quantized, meaning it can only take on certain discrete values. It is typically measured in units of h-bar, which is the reduced Planck's constant.

3. What are some identities regarding spin angular momentum?

One well-known identity is the commutation relationship between the x, y, and z components of spin angular momentum, which helps describe the uncertainty principle for spin. Another identity is the spin addition rule, which explains how the total spin of a system is related to the individual spins of its components.

4. How does spin angular momentum relate to magnetic moment?

Spin angular momentum and magnetic moment are closely related, as the spin of a particle generates a magnetic field. The magnitude of the magnetic moment is equal to the product of the spin and the gyromagnetic ratio, a constant specific to each type of particle.

5. What are some practical applications of understanding spin angular momentum?

Understanding spin angular momentum is crucial in many fields of physics, such as quantum mechanics and solid-state physics. It also has practical applications in fields like nuclear magnetic resonance (NMR) spectroscopy, which is used in medical imaging and chemical analysis.

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