Light-emitting diodes

Principle

Light-emitting diodes (LEDs) are pn junctions composed of GaAs or GaP. Depending on the desired wavelength of light, the substrates are doped with various elements. When the pn junctions are connected to a current source in the forward direction, electrons and holes flood the barrier layer and recombine there. When they do, the expended energy is released in the form of visible or infra-red light.
In the reverse direction, LEDs behave the same as normal diodes. However, the maximum reverse voltage is quite small. For some LED types, it is even less than 10 V.

Benefits

• No additional cable connections between the building blocks needed - clear arragned and quick setup
• Contact saftey due to puzzle blocks system
• Corrosion-free gold plated contacts
• Doubled earning sucess: Electric circuit diagram on top, real components can be seen unterside

Tasks

What are the characteristics of light-emitting diodes and what are they used for?

1. Investigate the relationship between current and voltage for a light-emitting diode in forward and reverse direction as well as the electrical power received by the diode.
2. Test the suitability of light-emitting diodes for determining the type of current and the polarity of the current source.