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Homework Help: Charge leakage of an electroscope

  1. Dec 1, 2009 #1
    1. The problem statement, all variables and given/known data

    We are doing an experiment with a radioactive 226 Radium source, demonstrating the ionizing power of alpha radiation using an electroscope. This is one of the assignments:

    Charge an electroscope (what is an effective way?); you will notice the gradual discharging of the electroscope through charge leakage.

    1) Explain in what way the leakage of charge takes place.
    2) In what way do you expect the discharging process to be affected by the proximity of the Ra-source?
    3) Is the position of the Ra-source with respect to the electroscope a critical factor?

    3. The attempt at a solution

    1) Two ways, the charge leaks to surrounding air and the charge is ionized by the Ra source.
    2) I expect that it won't be gradual, but instant. Once the radium source gets close enough so that the Helium particles have enough energy left over by the time they reach the electroscope, the particles will begin discharging it.
    3) It only needs to be close enough so that the particles will have enough energy left, after that the distance doesn't matter anymore.

    Anyone who could shed some light on whether or not these answers are correct?
    Last edited: Dec 1, 2009
  2. jcsd
  3. Dec 1, 2009 #2


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    Homework Helper

    1. It is not the charge that is ionized, but the air. The radiation will make the air more conductive.
    2. I hope it is not instant - that would be a powerful and dangerous radioactive source.
    3. The particles from the source will spread out in all directions from the source. Their intensity (number of particles per unit area) diminishes rapidly with distance from the source.
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