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!

Net charge and Electric field of a shell

  1. Nov 8, 2009 #1
    1. The problem statement, all variables and given/known data
    A cylindrical shell of radius 7.00 cm and length 240 cm has it's charge uniformly distributed on it's curved surface. The magnitude of the electric field at a point 19.0cm radially outward from its axis (measured from the midpoint of the shell) is 36.0 kN/C. Find (a) the net charge on the shell and (b) the electric field at a point 4.00 cm from the axis, measured radially outward from the midpoint of the shell.


    2. Relevant equations

    [tex]\Phi[/tex]_E= [tex]\int[/tex]E dA = qin/E_0

    3. The attempt at a solution


    [tex]\Phi[/tex]_E= E dA = qin/E_0
    = E[tex]\int[/tex] dA = EA= [tex]\lambda[/tex]l/E_0

    E(2[tex]\Pi[/tex]rl)= [tex]\lambda[/tex]l/E_0

    E= [tex]\lambda[/tex]/2[tex]\Pi[/tex]E_0r= 2k_e([tex]\lambda[/tex]/r)

    I'm not sure what else to do or if any of that is right.
     
  2. jcsd
  3. Nov 8, 2009 #2
    Looks right, but your Latex is difficult to read. Your basically using Gauss' Law to find the electric field at points external to the cylinder. Your equation would be great if you knew the line charge density (lambda), but you don't. Use the relation that you used in your derivation to replace lambda with the charge q.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook