1. The problem statement, all variables and given/known data Assume a free particle, V=0, in a infinite potential square well between -L/2 and L/2 solve for the wave function for this particle. 2. Relevant equations Time independent schrodinger equation 3. The attempt at a solution After arriving at the second order differential equation, I get a general solution of ψ=Acos(kx) + Bsin(kx) How do I go on to solve for A, B and k? I've plugged in the boundary conditions, but the solution is still quite indeterminate. I have to assume A=0, then ψ=Bsin(2n∏x/L) however, if I assume B=0, I get ψ=Acos([2n+1]∏x/L) which is correct? I do need to pick one before going onto normalising right?