1. The problem statement, all variables and given/known data A particle of energy E approaches a step barrier of height U. What should be the ratio E/U be so that the reflection coefficient is 1/2. 2. Relevant equations Transmission + Reflection = 1 Transmission = e^(-2a*alpha) a = mw∏/h alpha^2 = (8m∏^2/h^2)(U-E) Reflection = (k1-k2)^2 / (k1+k2)^2 3. The attempt at a solution So this is a little bit messy.. I assume most people that are going to help me are familiar with these basic transmission and reflection equations. Anyway is there a possible way to solve this problem an get a ratio that is JUST a number? wouldn't you always have other variables in it since it's talking about a completely undefined particle? there are no ways to get the m's and w's out of the equations right?