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: Gauss: Conducting Spherical Shell w/ Point Charge

  1. Feb 8, 2009 #1
    1. The problem statement, all variables and given/known data
    Consider a conducting spherical shell with inner radius 0.8 m and outer radius 1.3 m. There is a net charge 3 μC on the shell. At its center, within the hollow cavity, there is a point charge 3 μC.

    Determine the flux through the spherical Gaussian surface S, which has a radius of 0.4 m. Answer in units of N · m2/C.

    a= 0.8m
    b= 1.3m
    q1 = q2 = 3e-6 C

    2. Relevant equations

    Flux = E*A
    E = (kQ)/r^2
    A = 4pir^2

    3. The attempt at a solution

    I thought I could approach this in a very straight forward way: finding E of the point charge and multiplying it by the spherical shell's surface area (using the outer radius for both r's).

    So, E = (8.99e9*3e-6)/1.3^2 = 15958.6
    A = 4*pi*1.3^2 = 21.237

    EA = 3.389e5 N*m2/C, which is wrong. I'm not sure what I should do.
  2. jcsd
  3. Feb 8, 2009 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Your solution looks good to me. (Not sure why you used the outer radius, but it doesn't matter. For that matter, you could have just used Gauss's law directly.)
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook