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Homework Help: Alpha, beta particle radius of curviture

  1. Sep 29, 2010 #1
    1. The problem statement, all variables and given/known data

    see attachment

    2. Relevant equations

    3. The attempt at a solution

    35 kiloelectron volts = 5.60761762 × 10-15 joules

    I could calculate the velocity if I knew mass but that wouldn't help with the radius?
    I think that I need to find A from the energy but how do I do that?

    Attached Files:

  2. jcsd
  3. Sep 30, 2010 #2


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    Homework Helper

    The relevant equations are

    mv^2/r = qvB. Or

    mv = qrB.

    sqrt(2mE) = qrB. where E is the energy of the particle , m is the mass of the particle.

    Mass of β particle is the mass of the electron and mass of the α particle is equal to 4 times the mass of the proton.
  4. Sep 30, 2010 #3
    thanks that worked for the beta particle but not the alpha particle.
    sqrt(2*4*1.6726E-27*5.61E-15)=1.602E-19*r*1.1 then I solved that and got 0.05m and thats wrong!

    theres a similar Question in the text book but the energy is 40keV and B=1.5T the answer in the text book for the alpha particle is 19.3mm and when I try it I get 0.0525m???

    thanks for helping!
  5. Sep 30, 2010 #4


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    Homework Helper

    For alpha particle q = 2*e = 2*1.6*10^-19 C.
  6. Sep 30, 2010 #5
    Thanks heaps - problem solved!
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