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!

Homework Help: Invisible's Homework House

  1. Dec 4, 2004 #1
    Hi, I need help with this question:

    An ion with a charge-to-mass ratio of 1.10 x 10^4 C/kg travels perpendicular to a magnetic field (B = 9.10 x 10^-1 T) in a circular path (R = 0.240 m). How long does it take the ion to travel one revolution?

    I've found the speed that it travels....then what? How would I find the distance that it travelled? Do I use the circumference? :confused:

    I've decided....instead of posting a thread everytime I need help, I'm just going to have one thread and this is where I'll post my questions.
  2. jcsd
  3. Dec 4, 2004 #2


    User Avatar
    Science Advisor
    Homework Helper

    If the ion travels in a circular path then the distance it travels in one revolution must be the circumference of the circle.
  4. Dec 4, 2004 #3
    This is what I did:

    q/m = vB┴r
    (1.10 x 10^4 C/kg)(9.10 x 10^-1 T)(0.420 m) = v
    v = 2402.4 m/s

    C = (pie)d (I don't know how to make the symbol)
    C = (pie)(0.480 m)
    C = 1.507...m

    t = d/ = 1.507...m/2402.4 m/s = 6.28 x 10^-4 s

    Is this right?
  5. Dec 4, 2004 #4


    User Avatar
    Science Advisor
    Homework Helper

    I think you switched digits in R. You stated originally that R = 0.24 m but you seem to be using R = 0.42 in your calculation.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook