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Homework Help: Magnetic field question

  1. Sep 24, 2014 #1
    A 3.60 mC charge moving at 862 m/s travels at right angles to a magnetic field, and experiences a .00425 N magnetic force.

    Find the strength of the magnetic field.

    F = qvB (not sure if the right angle makes a difference in the equation.)

    B= .00425 /(3.60x10^-6)(862) = 1.37 T

    A 53.0 mC charge is now moving at 1300 m/s and 550 to the same magnetic field.

    Find the magnetic force exerted on the second charge.

    F = (53x10^-6C) (1300m/s)(550T) = 37.8 N

    Does this look correct? Also, I am wondering what if the angle was not a right angle? how would that differ the equation I would use..
  2. jcsd
  3. Sep 24, 2014 #2


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    Staff: Mentor

    F = qvB is true for a right angle between motion and magnetic field only, otherwise you need the cross-product of velocity and magnetic field.

    And 550 what? Is that an angle? 55°?
    The problem statement said you should use the magnetic field from the first subquestion. And 550T is not a reasonable field strength.
  4. Sep 24, 2014 #3
    Ahh yes I'm sorry I copy and pasted it over and didn't realize it put a zero. It is 55 degrees. yes.
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