mlab4_photoelectric_effect

mlab4_photoelectric_effect - PHY 252 Lab 2: the...

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PHY 252 Lab 2: the Photoelectric Effect Spring 2007 In this experiment you will use the photoelectric effect to measure the Planck constant h . While measurements of the Planck blackbody spectrum led to earlier measurements of h , precision mea- surements based on the photoelectric effect led to the first precise determination of h , and in 1926 R. A. Millikan received the Nobel Prize for these measurements. A phototube is illuminated by light of a known wavelength. Electrons are ejected from the photocathode with some kinetic energy E k . They are collected as anode current unless a variable retarding potential V stop is large enough to stop the electrons (at which point we refer to that voltage as the “stopping potential”). At this stopping potential V stop , all electrons with charge e , and thus kinetic energy E k = e · V , will be stopped, which can be described with E k = hc λ - φ = e · V stop , (1) where λ = c/ν is the wavelength of the incident light and φ is a work function of the cathode
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This note was uploaded on 01/25/2012 for the course PHYSICS 251 taught by Professor Staff during the Fall '11 term at SUNY Stony Brook.

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mlab4_photoelectric_effect - PHY 252 Lab 2: the...

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