1. The problem statement, all variables and given/known data Calculate the length of the space L in nm if an electron is trapped in one dimensional space of length L, and shows an absorption at 523nm due to transition from ψ2 to ψ3. 2. Relevant equations Energy expression for particle in box: Ev= (n2h2)/(8mL2) n=1, 2, 3.... 3. The attempt at a solution I don't understand what I am suppose to do with 523 nm. Once I know that I can continue. Please help with this. Thanks.