Angular Momentum (Modern Physics)

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SUMMARY

The discussion focuses on calculating the angular momentum of a hydrogen atom in the n = 3, l = 2 state. The possible values of total angular momentum (j) are determined to be 5/2 and 3/2. The magnitudes of total angular momentum (J) are calculated using the formula J = sqrt(j(j+1)), resulting in J values of sqrt(35)/2 hbar for j = 5/2 and sqrt(15)/2 hbar for j = 3/2. The z components of total angular momentum (mj) are also outlined, with values of ±5/2, ±3/2, and ±1/2 for j = 5/2 and ±3/2, ±1/2 for j = 3/2.

PREREQUISITES
  • Understanding of quantum mechanics concepts, specifically angular momentum.
  • Familiarity with quantum numbers (n, l, j).
  • Knowledge of the hydrogen atom's electronic structure.
  • Proficiency in using the formula J = sqrt(j(j+1)) for angular momentum calculations.
NEXT STEPS
  • Study the quantum mechanics of angular momentum in multi-electron atoms.
  • Learn about the addition of angular momentum in quantum systems.
  • Explore the implications of quantum numbers on atomic structure.
  • Review examples of angular momentum calculations in different quantum states.
USEFUL FOR

Students of modern physics, particularly those studying quantum mechanics and atomic structure, as well as educators looking for examples of angular momentum calculations in hydrogen atoms.

roeb
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Homework Statement


This problem is giving me a headache and unfortunately I can't find any example that is similar to it.
A hydrogen atom is in the n = 3, l = 2 state.

(a) What are the possible values of j?

(b) What are the possible values of the magnitude of the total angular momentum including spin?

(c) What are the possible z components of the total angular momentum?


Homework Equations





The Attempt at a Solution



(a)
I believe that jmax = l + 1/2
and jmin = l - 1/2 so...
jmax = 5/2
jmin = 3/2
so
j = 5/2, 3/2

(b)

J = L + S
J = sqrt( j (j+1) )

J1 = sqrt(35)/2 hbar --> (j =5/2)
J2 = sqrt(15)/2 hbar --> (j=3/2)


(c)

j = 3/2; mj = +- 3/2, +- 1/2
j = 5/2; mj = +-5/2, +-3/2, +-1/2


I am very unsure about this whole process. My book unfortunately doesn't have any examples of this process. Can anyone check my work and see if what I am doing is correct? In particular I am very unsure of part b, it just seems a bit strange to me despite following the formula.

Thanks
roeb
 
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it all looks correct!
 

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