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!

Coulomb force question

  1. Oct 8, 2006 #1
    A line charge of length L with lamba=const.(linear charge density) lies along the positive Z axis with its ends located at z=z0 and z0+L. Find the total force on the line charge due to a uniform spherical charge distribution with center at origin and radius a<z0

    Sooo here's what I DID

    I knew the total charge contained on the line charge was lamba*L, and the total charge contained in the sphere was 4/3 pi a^3 * rho where rho was its charge density, and it could be treated like a point particle with that total charge since the line charge didn't go inside it.

    So my vector going from the origin to my field point was r=zk(k unit vector in z direction)and r'=0 since the source point was on the origin,so R^2=z^2

    so the Force on a point on the line charge I took to be q*q'/r^2 in the z direction which was, after simplifying, (lamba*L*a^3*rho)/(3ez^2) where e is permitivitty of free space or whatever. so integrating over the whole line charge, ie F=S(allthat)*dz from z0 to z0+L, well, ALMOST gave me the right answer, I got an L^2 in the final answer when there should be just a single L

    so I think earlier when I was finding the force at a point on the line charge, I had to JUST use lambda and not the whole line charge lamda*L?
     
  2. jcsd
  3. Oct 8, 2006 #2
    I think you hav got the problem, and cahrge on each elemnent of the stick is Lam.dr.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Coulomb force question
Loading...