Start the CEcIL remote experiment.
Select a measured LED (see description of controls).
Using the slider (PC) or the + & – buttons (tablet), gradually set different values of electric voltage on the LED.
Read the voltage and current values and write them in the table.
Monitor the measured values in the table continuously and in case of larger gaps between the points of dependence measure the missing parts.
Repeat the same procedure for each LED. After measuring each LED, you can save the obtained experimental data on the disk of your PC.
Exit the remote task after measuring the required number of data (and save all files of experimental values!).
Open the selected experimental data file in a spreadsheet.
Plot the dependence of the electric current through the LED connected to an electric voltage on the graph. Check that the shape of the obtained dependence corresponds to the expected shape.
Select the points of the linear part of the dependence and interleave by a linear regression including display of its equation. Obtain the threshold voltage U* by determining the intersection with the horizontal axis (graphically and numerically).
The slope of the regression line corresponds to the dynamic (differential) resistance of the LED.
All V-A characteristics can be compared by plotting on a common graph.
