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Code Number: 7A10.33
Demo Title: Planck's Constant - LEDs
Condition: Good
Principle: Planck's Constant
Area of Study: Modern Physics
Equipment:
LED array, oscilloscope, variac, 6 volt transformer, mulitmeter if desired.
Procedure:
The LED's are designed to be powered off of 6 volts. Use the multimeter to check the voltage if you wish. Hook the oscilloscope across the current resistor and the other lead across the diode. With an xy display a sharp "knee" in the curve is clearly seen. A plot of the "knee" voltage for the 6 different wave lengths of the array should give you measurements for Planck's Constant.
References:
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