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Franck Hertz experiment - overheated tube

  1. Sep 29, 2010 #1
    1. The problem statement, all variables and given/known data
    What happens when the tube is (a) overheated or (b) too cool.

    2. Relevant equations

    3. The attempt at a solution
    I searched on google and almost all said:

    If the tube has been overheated, the emission current is small, and maxima and minima can hardly be recognized or seen at all ... On the other hand, when the tube is not sufficiently heated, the emission current is large and the maxima, especially those of a higher order, can hardly be seen. This is because, due to the low mercury pressure in the tube, discharge can place even at small voltages. When this is the case, the tube must be heated to a higher temperature.


    I am struggling to understand this. What is the emission current? Is it the current of electrons flowing from the cathode? And I also don't get why would maxima/minima can hardly be seen if this current is small/large.

    Please explain and thanks in advance
  2. jcsd
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