1. The problem statement, all variables and given/known data Estimate the ground state energy (eV) for an exciton in Si. εSi = 12 ε = 1.0359×10−10 Effective massesme* = 0.26me mh* = 0.36me effective mass = 0.15me Values of h6.626×10−34 J⋅s 4.136×10−15 eV⋅s Values of ħ Units1.055×10−34 J⋅s 6.582×10−16 eV⋅s 2. Relevant equations E1 = me4/(8*h2ε02) E = m*e4/(8*h2ε2) 3. The attempt at a solution 0.15(9.11e-31)e^4/[8(6.626e-34)^2(1.0359e-10)^2] = 0.15(9.11e-31)54.59815/[8(6.626e-34)^2(1.0359e-10)^2] [link to wolfram for this calculation] = 1.98×1056 J This seems way too big! It's even bigger in eV: 1.24×1075 I would really appreciate it if someone could help point out where I went wrong. It seems like most want to beat around the bush...or maybe everyone that's helped me here is just in a rush. That epsilon I'm not 100% sure about either.