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Homework Help: [101] Magnetic field strength in fN

  1. Apr 13, 2008 #1
    [SOLVED] [101] Magnetic field strength in fN

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

    You have arranged that the magnetic field in a particular region of space is due North with a value of 0.01 T. An electron enters the field traveling to the West with a speed of 0.05 of the speed of light. As a result, the electron experiences a magnetic force which is upwards.

    (a) What is the strength of this magnetic force, in fN? (NOTE: The "f" stands for "femto", which is 10-15.)

    (b) What is the amount of the resulting acceleration of the electron? (NOTE: Get the mass of an electron from the inside back cover of your textbook.)

    2. Relevant equations


    3. The attempt at a solution
    B will be very strait forward once I have answered a. I already know the strength of the magnetic force (B) in Tesla. So, it seems that I just need to convert tesla to femto newtons. Can someone lead me in the right direction?

    I am not very familiar with this concept.

    Thank you SO much!
  2. jcsd
  3. Apr 13, 2008 #2


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    Science Advisor

    Tesla is a measure of magnetic field strength, not force. For a charged particle moving through a magnetic field, the force it feels is given by F=qVxB where q is the charge on the particle, V is its velocity, and B is the magnetic field. The x indicates cross product. Again, the Tesla value is a FIELD strength, not a force.
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