Calculating Width of One-Dimensional Box for Photon Emission

[Dinno]

Homework Statement

When a hydrogen atom undergoes a transition from the n=2 state to the n=1 level, a photon
with \lambda=122nm is emitted.

a)If the atom is modeled as an electron in a one-dimensional box, what is the width of the box in order for the n=2 to n=1 transition to correspond to emission of a photon of this energy?

Homework Equations

The Attempt at a Solution

Do not know what equations to use to solve this problem

 

[kuruman]

What is the expression that gives the energies of a particle in a one-dimensional box? Start from there. Match the energy difference from n =2 to n = 1 to the energy of the 122 nm photon.