1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Magnetic Field Problem!

  1. Nov 19, 2012 #1
    1. The problem statement, all variables and given/known data

    An electron (m= 9.11 x 10^-31 kg) enters a downward magnetic field of 5.00 x 10^-1 T with a velocity of 6.50 x 10^6 m/s West. Calculate the radius of the circular path it will follow when it is travelling within the magnetic field.

    m = 9.11 x 10^-31 kg
    v = 6.50 x 10^6 m/s West
    B = 5.00 x 10^-1 T
    q = -1.60 x 10^-19 C


    2. Relevant equations

    Fm = qvB
    Fc = mv^2/r
    Fm = Fc

    3. The attempt at a solution

    Fm = qvB
    = (1.60 x 10^-19 C)(6.50 x 10^6 m/s)(5.00 x 10^-1 T)
    = 5.2 x 10^-13 N

    Fm = mv^2/r
    r = mv^2/Fm
    = (9.11 x 10^-31 kg)(6.50 x 10^6 m/s)^2 / (5.2 x 10^-13 N)
    = 7.40 x 10^-5 m

    I feel like I may have done this question wrong...
     
  2. jcsd
  3. Nov 19, 2012 #2

    Delphi51

    User Avatar
    Homework Helper

    It looks good!
    May I offer a suggestion?
    It is a little more efficient and quite a bit clearer if you write it up this way:
    The centripetal force is provided by the magnetic force
    Fm = Fc
    qvB = mv²/r
    qB = mv/r
    r = mv/(qB)
    Put in the numbers and run it all through the calculator in one go, so no rounding takes place until you write the final answer.
     
  4. Nov 20, 2012 #3
    Thank you very much!
    I really appreciate your advice as well. :)
     
  5. Nov 20, 2012 #4

    Delphi51

    User Avatar
    Homework Helper

    Most welcome and good luck with Physics.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Magnetic Field Problem!
Loading...