1. The problem statement, all variables and given/known data Show for a simple square lattice that the kinetic energy of a free electron is higher at the corner of the first zone than at the midpoint a side face by a factor of 2. 2. Relevant equations Simple geometry. 3. The attempt at a solution I think I know how to solve, but I am not completely sure I understand the question. The position of the electron refers to the position of its k-vector in k-space right? Well this is not real space, and I cant really see how this has anything to do with the lattice being square in real space.