7 Quantum Physics 7.6 Planck's "quantum of action" and photoelectric effect
P2510402
Planck's "quantum of action" and photoelectric effect (line separation by interference filters)
Photoelectric current intensity I as a function of the bias voltage at different frequencies of the irradiated light.
Principle A photocell is illuminated with monochromatic light of different wavelengths from a filament lamp with interference filters. The maximum energy of the ejected electrons in the photo-cell depends only on the frequency of the incident light, and is independent of its intensity. The stopping voltage Uo at different light frequencies is determined by the U/I caracteristics of the photocell and plotted over the corresponding light frequency f. Planck's quantum of action or Planck's constant (h), is determined from this graph .
Related Experiment Planck's "quantum of action" and extern photoelectric effec effect (line separation by a diffraction grating) P2510502
Tasks 1. To determine Planck's quantum of action from the photoelectric voltages measured at different wave lengths What you can learn about ▪ ▪ ▪ ▪ ▪ ▪
External photoelectric effect Work function Absorption Photon energy Anode Cathode
Main articles Interference filters, set of 3 Interference filters, set of 2 Universal measuring amplifier Photocell for h-determination, with housing Power supply 0...12 V DC/ 6 V, 12 V AC, 230 V Rheostat, 100 Ohm , 1.8A Experiment lamp 5 DMM with NiCr-Ni thermo couple
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Max Planck 1918, Nobel Prize in Physics