1. The problem statement, all variables and given/known data Find donor-electron ionziation energy of silicon crystal. Electron effective mass mc=.98mo and dielectric constant ε/εo=12.3 2. Relevant equations I use the ED=-(1/4πε)2*[(mc*e4) / (2*(h/2π)2)] 3. The attempt at a solution My answer of -1.415x10-54 does not seem right. I solved for mc and ε from given equations in the problem and plugged in. Is this correct or have I made a mistake?