AIM OF THE EXPERIMENT: To determine the value of Planck’s constant ‘h’ by using light emitting diode.
APPARATUS:Regulated DC power supply, Light emitting diodes, Digital voltmeter and Digital microammeter.
PRINCIPLE: Planck’s constant ‘h’ is given by,
h = eVl/c = eV/n where ‘e’ is the electron charge, ‘V’ the turn on voltage corresponding to a LED which emits light of wavelength ‘l’, frequency ‘n’and ‘c’ the velocity of light. If we draw a graph between turn on voltage ‘V’ and frequency ‘n’, from the slope of the graph, we can determine the Planck’s constant
PROCEDURE: Connections are made as shown in figure. Turn on voltages of different light emitting diodes are taken and plotted against corresponding frequencies. Slope of the graph will give Planck’s constant.
APPARATUS:Regulated DC power supply, Light emitting diodes, Digital voltmeter and Digital microammeter.
PRINCIPLE: Planck’s constant ‘h’ is given by,
h = eVl/c = eV/n where ‘e’ is the electron charge, ‘V’ the turn on voltage corresponding to a LED which emits light of wavelength ‘l’, frequency ‘n’and ‘c’ the velocity of light. If we draw a graph between turn on voltage ‘V’ and frequency ‘n’, from the slope of the graph, we can determine the Planck’s constant
PROCEDURE: Connections are made as shown in figure. Turn on voltages of different light emitting diodes are taken and plotted against corresponding frequencies. Slope of the graph will give Planck’s constant.
RESULT:
Planck’s constant =
