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#Mon Aug 09 12:01:57 CEST 2010
Text__H-UscKOdEd-WfYQ0GneCwQ_title=Franck Hertz Experiment
Text__H-UscKOdEd-WfYQ0GneCwQ_text=<p>In 1913/1914, Franck and Hertz demonstrate that the collisions between electrons and gas molecules (in this case, neon) are elastic as long as the energy of the electrons lies below a certain threshold. When the threshold energy is attained, inelastic collisions occur and the neon radiates red light. According to quantum theory, the levels of energy transmitted are whole-number multiples of the threshold energy. This is why we observe discrete layers lighting up one after the other in a neon tube.</p>