# Potential step, classical vs quantum mechanics

1. Apr 30, 2012

### wanderlust.xx

1. The problem statement, all variables and given/known data

We have the potential step

$U(x) = 0, \ x < 0 \\ U(x) = U_0, \ x>0$

2. Relevant equations & 3. The attempt at a solution

If we measure, for example, the magnitude of the transmitted current $j_T$ over the reflected current $j_R$, so

$\left| \dfrac{j_T}{j_R} \right|$

then classically we would expect no reflection for $x<0$, so we would have the reflected current as 0, whereas here if that were the case then... would this ratio be infinite?

I'm not sure if this is correct. I believe that the ratio involving the current of the incident and reflected $\left| \dfrac{j_R}{j_{inc}} \right|$ should classically be 0 since there's no reflected wave.

Just wanted to double check, really!