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Homework Help: Stationary particle in a laser beam

  1. Mar 6, 2007 #1
    1. The problem statement, all variables and given/known dataA stationary particle of charge q = 3.0 10-8 C is placed in a laser beam whose intensity is 2.5 103 W/m2.

    (a) Determine the magnitude of the electric force exerted on the charge.

    (b) Determine the magnitude of the magnetic force exerted on the charge.

    2. Relevant equations
    Force on a charge--> F=qE
    S = cu
    u = (1/2)εo*E^2

    3. The attempt at a solution
    a.) i am given S and i know c so i can find u by S/c = u.
    now that i have u i can solve for E using u = (1/2)εo*E^2.
    I multiply E times q to get F.
    sounds easy enough and makes sense to me, however i am doing something wrong here huh?

    b.) i know that the magnitude will be zero since the charge is stationary.
  2. jcsd
  3. Mar 7, 2007 #2

    Meir Achuz

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    Science Advisor
    Homework Helper
    Gold Member

    Looks OK to me.
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