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Exam Quantum Transport: results

I will leave for vacations soon. In order not to dissappoint the sudents with the delay of the marks, I had to check the exam papers of quantum transport quickly. I’ve worked over the weekend and finally done the job today.

The exam consisted of two parts: the problem and multiple-choice questions (mcq). Roughly, problem checks the attendance of problem-solving sessions, while mcq check if a student has re-read the lecture material before the exam:) The mcq are very accurate tool: in many cases, I can see at which lecture a student stopped re-reading of the lecture material.

The distribution of the answers to mcq was rather standart, perhaps with the maximum slightly larger than expected. However, there was a problem with the problem.

Let me explain the problem without formulas. There are two ways to solve scattering problems considered in the course. Way 1 employes summation of elementary scattering trajectories, is easy and constructive for elementary setups, but is too complicated for just a bit more complex situations. Way 2 is more formal: it requires to make a system of linear equations for amplitudes of reflected and transmitted waves that has to be solved subsequently. Both ways, the difference between them and their formal mathematical similarity have been explicitly explained in course of the lectures and problem sessions. The formulation of the exam problem clearly suggested: do it in way 2.

Oh. Vast majority of the students did it in way 1. The success to follow the way has been varying while the suffering remained rather invariant. Now I understand why the students looked so gloomy. Now it’s my turn to look so: I’ve so carefully paved way 2 to lead to examination sucsess, and almost nobody took it.

Besides a point in the problem that we regarded as ultimately trivial appeared to be an almost universal stumbling block for both strong and weak. Oh. These apparent misunderstandings made the evaluation a complicated and painful procedure. The results could be better, but, after all, they are not so bad.

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