Crude Probability calculation for tunneling

[decerto]

Say I have a potential barrier that is 4eV higher then an electrons energy and 5x10^-11 wide. Just by considering the change in amplitude of the wave function from the entry into the barrier vs the exit I am asked to make a rough approximation for the probability of tunnelling. I get the amplitude at entry is 1 and exit is 0.00594. Now is 0.00594 a good approximation for the probability of tunnelling or would I need to do anything else to do it.

This isn't homework it's practice for an exam which I have tomorow

 

[The_Duck]

Recall that you need to square amplitudes to get probabilities.

 

[jtbell]

It might also help if you tell us how you calculated the amplitude at exit so we can check your procedure.