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: Magnetic field

  1. Feb 26, 2006 #1
    Hi, I have this problem and I need some explanation and help to solve it:

    An electron is injected at t=0sec with a velocity of vo =(2*10^6 m/s) i into a region with parallel electric field E=(1500V/m)j and B=(-.2T)j,respectively.
    Calculate the subsequent motion.

    What I did is that I know that the motion will be a circular one.
    then I computed R =m*v/(q*B)
    Can I compute R this way since we have electric and magnetic fields together??

    Also How can I find the acceleration? when I do V2/R I dont get the right answer at the back of the textbook.

    Thank you
  2. jcsd
  3. Feb 26, 2006 #2
    Since there's an electric field, the magnitude of it's velocity increases, so the radii will chage. You can plug the Lorentz force into Newton's 2nd law.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook