The Photoelectric Effect A Determination Of Planck S Constant
Reviewer’s Name: Sanjeev Mishra
UMN ID Number: 4585009
The Photoelectric Effect: A Determination of Planck’s constant
Ian E. Jaeger
School of Physics and Astronomy, University of Minnesota – Twin Cities
116 Church St. S.E., Minneapolis, MN 55455
Abstract
The photoelectric effect was explored to determine an experimental value of Planck’s constant, h. Included is a brief introduction to the history leading up to Einstein’s discovery of the photoelectric effect as well as the theory behind it. To determine h, multiple intensities of light were shined upon a cathode/anode apparatus and current and stopping potentials were measured. The weighted mean of the two values determined from different light intensities is (4.141 ± .008924) × 10-15 eV∙s, which is within .560σ of the world value of h. The independence of electron kinetic energy and incident light intensity is shown from the experiment. Also included is a brief analysis of the determined work function of the cathode.
I. Introduction
Through the latter portion of the 19th century, many experiments developed a relationship between light and electrical energy. The first was that of the discovery of the photovoltaic effect in 1839 by French physicist A.E. Becquerel [1], by which electrical energy is produced from light incident upon a metal. Subsequent experiments further detailed the relationship between light and electricity, namely that of Hertz in 1887 [2], showing that the maximum distance allowing electrical discharge between two metals increases when the metals are exposed to light, and that of Lenard in 1902 [3], showing that the kinetic energy of electrons emitted from the surface of a metal is proportional to frequency. Lenard’s experiment provided a direct contradiction to Maxwell’s wave theory of light, as he observed that the energy of emitted electrons was independent of the incident light intensity.
These experiments resulted in the need for a new explanation of light. This was
UMN ID Number: 4585009
The Photoelectric Effect: A Determination of Planck’s constant
Ian E. Jaeger
School of Physics and Astronomy, University of Minnesota – Twin Cities
116 Church St. S.E., Minneapolis, MN 55455
Abstract
The photoelectric effect was explored to determine an experimental value of Planck’s constant, h. Included is a brief introduction to the history leading up to Einstein’s discovery of the photoelectric effect as well as the theory behind it. To determine h, multiple intensities of light were shined upon a cathode/anode apparatus and current and stopping potentials were measured. The weighted mean of the two values determined from different light intensities is (4.141 ± .008924) × 10-15 eV∙s, which is within .560σ of the world value of h. The independence of electron kinetic energy and incident light intensity is shown from the experiment. Also included is a brief analysis of the determined work function of the cathode.
I. Introduction
Through the latter portion of the 19th century, many experiments developed a relationship between light and electrical energy. The first was that of the discovery of the photovoltaic effect in 1839 by French physicist A.E. Becquerel [1], by which electrical energy is produced from light incident upon a metal. Subsequent experiments further detailed the relationship between light and electricity, namely that of Hertz in 1887 [2], showing that the maximum distance allowing electrical discharge between two metals increases when the metals are exposed to light, and that of Lenard in 1902 [3], showing that the kinetic energy of electrons emitted from the surface of a metal is proportional to frequency. Lenard’s experiment provided a direct contradiction to Maxwell’s wave theory of light, as he observed that the energy of emitted electrons was independent of the incident light intensity.
These experiments resulted in the need for a new explanation of light. This was