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Homework Help: Electric and magnetic fields

  1. Mar 23, 2015 #1
    1. The problem statement, all variables and given/known data

    The below region of space shown has uniform electric and/or magnetic fields, dependent on the conditions listed for cases A-G. Identical positively charged particles enters these regions with the same velocity.

    Rank the magnitude of the force on the particle just after it enters these regions for cases A-G from greatest to least.


    2. Relevant equations

    F = qE + qv x B
    F = qE
    Fb = qvBsin(*)

    3. The attempt at a solution

    A) Since the particle is positive(+) I said there would be a force F namely ( ---> ) on the particle.

    B) When only B is present there is no force on the particle, Fb = qvBsin(0) = 0. This is because both B and V are parallel.

    C) Same as A: ( ---> )

    D) Same as A: ( ---> )

    E) Here the direction of the force changes but its magnitude remains the same so: ( <--- )

    F) There is an upwards force in this case. However, its magnitude is the same as was in A.

    G) I have this as being two forces on the particle so G is the largest.

    Overall I ranked them as follows: G>A=C=D=E=F>B

    Not sure if I did these correctly any help would be appreciated.

  2. jcsd
  3. Mar 23, 2015 #2


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    Sounds ok to me.
  4. Mar 23, 2015 #3
    Wait... you mean I got it right.. like on my own ._. I think I will go have a drink!
  5. Mar 23, 2015 #4


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    Science Advisor
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    Sure, have a drink. I can't see anything wrong with your logic.
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