Homework Help: Step up and Step down Potentials

1. Apr 28, 2012

hectorzer

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

What fraction of a beam of 8 eV electrons is reflected by a potential step up of height 6 eV? What fraction is reflected from a step down of 6eV?

2. Relevant equations

R=$(\frac{k_{1}-k_{2}}{k_{1}+k_{2}})^{2}$

Exchange $k_{1}$ and $k_{2}$ for the step down potential.

$k_{1}$=$\frac{\sqrt{2mE}}{h/2pi}$

$k_{2}$=$\frac{\sqrt{2m(E-U0)}}{h/2pi}$

3. The attempt at a solution

I got 1/9 for the step up.

But I got the same for the step down potential, which I don't think is right. Am I doing anything wrong for the step down potential? Or should you get the same answer for the step down as for the step up?

Last edited: Apr 28, 2012
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