5M10.55 - LED's

Code Number:
Demo Title:
Characteristics of Light Emitting Diodes
Area of Study:
Electricity & Magnetism
LED's - Many, Wave Generator, Batteries, Transformers, and Oscilloscope. LED Rainbow, Genecon Generator, 0 to 12 Volt Power Supply, PASCO Function Generator.

The LED Rainbow may be used in a variety of ways.  It is designed to show the turn on voltage of each color LED which is different for each color.  You may use the genecon generator to show this but you will have to crank very fast to get the purple (UV) LED's to light.  Using the power supply that can go from 0 to 12 volts will be easier, but you will see that the turn on voltages of the Red, Orange, and Yellow LED's are very close together.  A very cool way to use this display is to use the PASCO function generator as the power source.  Set the generator to a ramping voltage with a 0.18 Hz. frequency and maximum voltage (10 volts).  NOTE: you will have to short across one of the purple (UV) LED's as the function generator is limited to 10 volts maximum output.  This will allow the other 3 LED's in that section to light as the voltage ramps up.  

Select the LED for the demonstration you wish to show.  Many of our other demonstrations also use LED's in some form and are available for new LED demonstrations if needed.

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Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.