7A10.33 - Planck's Constant - LED's

Code Number:
Demo Title:
Planck's Constant - LED's
Planck's Constant
Area of Study:
Modern Physics
LED array, oscilloscope, variac, 6 volt transformer, mulitmeter if desired.

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.

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