1. Not finding help here? Sign up for a free 30min 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!

Radius of path of electron in a magnetic field

  1. Jul 25, 2006 #1
    # Electrons are moving in a uniform magnetic field of 50 Oersted having a velocity of 8.8 x 10^6 cm/sec. What is the radius of the circular path they follow?
    I solved it in the following way:
    In C.G.S system 1 Gauss = 1 Oersted (In vacuum)
    So, B = 50 Gauss
    V = 8.8 x 10^6 cm/sec
    Let e be the charge of the electron, r be radius of its circular path and m be its mass.
    e = 1.6 x 10^(-19) Coulomb = 4.8 x 10^(-10) Stat Coulomb
    m = 9.1 x 10^(-28) grams
    In a perpendicular magnetic field,
    BeV = {m(V^2)}/r
    r = (mV)/(Be)
    Solving I get,
    r = 3.3 x 10^(-13) cm
    I think somewhere I have gone wrong as the radius is too small. Please help.
  2. jcsd
  3. Jul 25, 2006 #2
    In cgs units the formula for the Lorentz force is (qv/c) x B. The final formula should read r = (mVc/Be). This gaves a much more reasonable answer.
  4. Jul 27, 2006 #3
    I have learnt the expression for Lorentz force in C.G.S system.Thanks.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?