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Homework Help: Velocity filter question

  1. Aug 28, 2011 #1
    1. The problem statement, all variables and given/known data
    In the figure (see attached) what is the velocity of the charged particle to the nearest tenth of a m/s that will allow it to travel undeflected through the crossed magnetic field if E = 6852 N/C and B = 3.6 T?


    2. Relevant equations

    F = E*q + q*V*B

    3. The attempt at a solution

    Okay, so this is an online physics practice thing (for Giancolli) I was assigned for AP work. It's known for giving wrong (but close) answers, so don't be afraid to tell me that I'm doing this right (or wrong). But the answer I got is very close to the answer it gave me.

    Anyway, here is my attempt:

    E*q = q*V*B
    cross out q

    E = V*B

    V = E/B

    E = 6852 N/C
    B = 3.6 T

    V = 1903.3 m/s


    Thanks,

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



    2. Relevant equations



    3. The attempt at a solution
     

    Attached Files:

  2. jcsd
  3. Aug 28, 2011 #2

    PeterO

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    Homework Helper

    Calculations look OK. Given the original data - especially the B = 3.6 - it indicates you should only give your answer to 2 figures, so 1.9 x 103 m/s

    note that 1900 m/s is not correct, because if you, even mistakenly, decide to give too many figures, those extra figures have to be correct.
     
  4. Aug 28, 2011 #3
    Thanks!
    And the online thing doesn't let us (for most questions) put in scientific notation
     
  5. Aug 28, 2011 #4

    PeterO

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    Homework Helper

    In that case, 1900 might be "their" form of 1.9 x 103
     
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