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Homework Help: Pulsing beam of electrons

  1. Nov 5, 2011 #1

    Oshada

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

    ISdSt.jpg

    2. Relevant equations



    3. The attempt at a solution

    I'm at a loss as to starting the problem. Any help is appreciated!
     
    Oshada, Nov 5, 2011
  2. jcsd
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  3. Nov 5, 2011 #2

    gneill

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    Staff: Mentor

    What is the relationship between current and charge?
     
    gneill, Nov 5, 2011
  4. Nov 6, 2011 #3

    Oshada

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    i = dQ/dt, but I can't figure out how to derive/integrate here :(
     
    Oshada, Nov 6, 2011
  5. Nov 6, 2011 #4

    gneill

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    Staff: Mentor

    No integration is required. You're given the current (0.5 A) and the time that it flows for each pulse (0.10 μs). If 0.5 A flows for 0.10 μs, how much charge has moved?
     
    gneill, Nov 6, 2011
  6. Nov 6, 2011 #5

    Oshada

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    Thank you very much, I forgot the elementary relation Q = it. I got 3.1 * 10^11 electrons for a) which is the right answer :)

    For part b), do we just divide average current per pulse by number of pulses per second?
     
    Oshada, Nov 6, 2011
  7. Nov 6, 2011 #6

    gneill

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    Staff: Mentor

    The average current will be given by the total charges moved in a second, divided by one second. You've found the charge q moved per pulse, and you know the number of pulses per second, so...
     
    gneill, Nov 6, 2011
  8. Nov 6, 2011 #7

    Oshada

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    Yup, got it. Part c) ?
     
    Oshada, Nov 6, 2011
  9. Nov 6, 2011 #8

    gneill

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    Staff: Mentor

    What are the units of power? What's the energy per charge? Per pulse?
     
    gneill, Nov 6, 2011
  10. Nov 6, 2011 #9

    Oshada

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    Again, I have forgotten that electrons having an energy of 50 MeV have been accelerated across 50 MV. Thanks!
     
    Oshada, Nov 6, 2011
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