What does it work for?

[Ryaan Pal 1L]

When it comes to particle-in-a-box problems, since photons don't have a rest mass, does that mean we can't apply these types of problems to photons?

[Yareli Cervantes 2C]

I believe we can still manage to adapt this situation to make it work in the case of a photon. For example, if a photon were to be in a restricted area we can find the quantization of energy levels for such photons in said tight space.

[Joanna_Sung_3F]

You are absolutely correct that photons have no rest mass. However, the particle in the box model is really just there to show that there are limitations and restrictions to a bonded electron. The model would still be helpful to apply to models of photons, where the energy is quantized. I may be wrong, but generally I think for photons we should still focus more on the energy shell diagrams instead.