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UPSC Combined Geo-Scientist

Chemist

  • 3 descriptive papers
  • 200 marks each
  • 3 h per paper

Mains Paper II covers physical chemistry.

UPSC Combined Geo-Scientist, Mains · 2021 · Mains Paper II

Q14(a). Degeneracy in a cubic box; states with E = 101h²/8mL²

Question

What is degeneracy? Illustrate with the cubic box of length L. How many eigenstates are there with energy equal to 101h²/8mL²?

Answer in brief

Degeneracy: different eigenstates with the same energy. For E = 101h²/8mL², nx² + ny² + nz² = 101 has three sets, {1,6,8}, {2,4,9}, {4,6,7}, each with 6 orderings: 18 eigenstates.

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Coversdegeneracyparticle in a cubic boxaccidental degeneracyeigenstatesthree-dimensional box

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