1. The problem statement, all variables and given/known data Suppose a 12.0eV electrons approach a potential barrier of height 4.2eV. For what barrier thickness is the reflection at a maximum? Known: v_0=6.7*10^(-19)J E=1.9*10^(-18)J m=9.11*10^(-31)kg hbar=1.055*10^(-34)J*s (I have converted from eV to J to make the units work) 2. Relevant equations T=(1+(v_0)^2/(4E(E-V0))sin2(qL))^(-1) q=sqrt(2m(E-v_0))/hbar T+R=1 (Where T is the transmission probability and R is the Reflection) 3. The attempt at a solution q=sqrt(2m(E-v_0))/hbar=sqrt(2(9.11*10^(-34))((1.9*10^(-18)-6.7*10^(-19)))/(1.055*10^(-34) so then q=1.42*10^10 I plugged in q into my equation for T and then the v_0 and the E for the electron. I set all of it equal to zero, but I think that's my downfall. Conceptually T cannot be zero because L would have to reach infinity. I am not sure what is means by R being a maximum (aka L is a minimum) without setting T=0.