1. The problem statement, all variables and given/known data You want to confine an electron and you want to know for certain that the electron's speed is no more than 66 m/s. What is the length of the smallest box in which you can do this? A) 2.8 × 10^-6m B) 1.4 × 10^-6m C) 1.1 × 10^-5m D) 5.5 × 10^-6m 2. Relevant equations There are two equations that could be used: E = (1/2m)(hn/2L)^2 or E = (h^2/8mL^2)(n^2), where n = 1, 2, 3, 4... 3. The attempt at a solution I understand that I will be solving for L. However, I don't understand how v = 66 m/s will plug into either of the equations above. Also, I'm not sure how to know what to plug in for n. I know the answer is D.) 5.5 x 10^-6m, but I have no idea how they got that answer. Assistance would be greatly appreciated.