# Homework Help: Energy levels for a 3D cubical box

1. Apr 2, 2013

### cytochrome

1. The problem statement, all variables and given/known data
Find the energies of the second, third, fourth, and fifth levels for the three-dimensional cubical box. Which are degenerate?

2. Relevant equations
E = h^2/8mL^2 (n^2 sub x + n^2 sub y + n^2 sub z)

3. The attempt at a solution
The levels would be degenerate if one of them occupied two or more different states, or if two occupied the same state, correct?

I'm lost on what to use for n_subx, n_suby, and n_subz in the problem. I'm pretty sure it's not Pythagorean

2. Apr 2, 2013

### cytochrome

I've found that (1,1,1) = 3, (1,1,2) = 6

and 6 is degenerate since it could be (1,2,1) or (2,1,1).

But do these correspond to n = 3 and n = 6?

3. Apr 3, 2013

### clamtrox

nx, ny and nz are positive integers, so 1, 2, 3,...

Clearly (1,1,1) is the ground state, and (1,1,2) is the first excited state. What's the second one? Is it (1,2,2) or (1,1,3)?