  This is the problem of the 8$^\mathrm{th}$ International Experimental Physics
Olympiad (EPO). The task of the EPO8 is to determine Plank constant
$\hbar=h/2\pi$ using the given set-up with LED. If you have an idea how to do
it, do it and send us the result; skip the reading of the detailed step by step
instructions with increasing difficulties. We expect the participants to follow
the suggested items -- they are instructive for physics education in
general.Only the reading of historical remarks given in the first section can
be omitted during the Olympiad without loss of generality. Participants should
try solving as much tasks as they can without paying attention to the age
categories: give your best.
