Franck and hertz had designed a vacuum tube for studying energetic electrons that flew through a thin vapor of mercury atoms. Transitions between these orbits may take place only when the atom absorbs or emits quantized packets of energy e hc. One year after bohrs theory of quantized energy states. The electronmercury collision experiment of franck and hertz 1, for which they won. James franck and gustav hertz conducted an experiment in 1914, which demonstrated the existence of excited states in mercury atoms. The franckhertz experiment makes it possible to observe the quantization of energy states in an atom. Franck and hertz directed lowenergy electrons through a gas enclosed in an electron tube. The franckhertz experiment experiments experimental physics i. One hundred years of the franckhertz experiment request pdf. The franck hertz experiment was the first electrical measurement to clearly show the quantum nature of atoms, and thus transformed our understanding of the world. Study of quantized excitation of neon atoms by inelastic scattering and determine the excitation energy. Modern experimental physics introduction for physics 401. In 1914, james franck and gustav hertz performed an experiment which demonstrated the existence of excited states in mercury atoms, helping to confirm the.
They touch on important themes in the development of modern physics. It confirms the prediction of quantum theory that electrons occupy only discrete, quantized energy states. These experiments measure two phenomena encountered in collisions between electrons and atoms. They discovered that, when an electron collided with a mercury atom, it could lose only a.
The franckhertz experiment was the first electrical measurement to clearly show the quantum nature of atoms, and thus transformed our understanding of the. Franckhertz experiment, in physics, first experimental verification of the existence of discrete energy states in atoms, performed 1914 by the germanborn physicists james franck and gustav hertz. Many experiments were once nobelprizeworthy efforts. Some will provide the insight to understand advanced courses. The franckhertz experiments, 19111914 experimentalists.
Some are just too new to be discussed in textbooks. In this ex periment, electrons are accelerated and pass through mercury vapor, where they lose energy by inelastic scattering in quantized steps. This explains the spectral lines given off by an excited element, such as described by rydbergs formula for the series of. The franckhertz experiment, first undertaken shortly after bohrs theory of the atom was pre sented, provided one of the early indications that atoms had discrete energy levels. Points out that the frankhertz experiment was one of the earliest indications of the existence of internal energy states within the atom. It was presented on april 24, 1914, to the german physical society in a paper by james franck and gustav hertz.
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