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Homework Help: Magnetic Forces and Magnetic Field

  1. Oct 24, 2009 #1
    1. The problem statement, all variables and given/known data

    A charged particle with a charge-to-mass ratio of |q| / m = 5.7x10^8 C/Kg travels on a circular path that is perpendicular to a magnetic field whose magnitude is 0.72 T.

    How much time does it take for the particle to complete one revolution?

    2. Relevant equations

    errrr.. I have no clue where to start with

    3. The attempt at a solution

    :( :(

    Thank you for your help...
  2. jcsd
  3. Oct 24, 2009 #2

    i tried to work it tho...not like Im just posting a new thread HEY GUYS COULD U PLEASE DO THIS FOR ME??

    the trouble im having is that I can't link t with all my magnetic formulas.... and I've never heard of charge mass ratio...

    i tried to work out hte velocity but... not enough data for it...

    anyway physicists we need you!!!
  4. Oct 24, 2009 #3


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    because the particle is moving on a circular path,
    so Fm=Fc
    rearrange the formula to q/m=?, then solve for the radius
    then use the radius to find the circumference,
    where d is the circumference
    Hope that helps
    Last edited: Oct 24, 2009
  5. Oct 24, 2009 #4
    hmmm yea :( indeed... damn it... sorry im med student not a physicist...

    that was easy... :*( :*(

    F = q v b sin 90
    F = qvb

    F = mv^2 / r ... obviously since a = v^2/r since it is a centri. force...

    qvb = mv^2/r
    q/m = v^2/rB
    5.7x10^8 C/Kg = v/rB since v must be 2pi.... :(

    5.7x10^8 C/Kg x r = 2pi/0.72T

    r = 1.53 x10^8 s

    thank you so much... this is the correct answer... thanx heaps :)
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