(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

We have a conducting and grounded wall for [tex]z<0[/tex], so [tex]\Phi=0[/tex] for [tex]z<0[/tex]. In front of this wall, we place a homogeneous charged sphere with radius [tex]R[/tex] and total charge [tex]Q[/tex]. The center of the sphere has a distance of [tex]a[/tex] to the front of the wall.

http://david.muelheims.googlepages.com/image_charges.png [Broken]

I need to find the electrostatic potential [tex]\Phi(\vec{x})[/tex] for [tex]z>0[/tex] with the method of image charges.

I just need the potential outside the sphere. I do not need to determine the potential inside the sphere.

So... Where do I place the image charges?

2. Relevant equations

All electrostatic equations.

3. The attempt at a solution

I placed a first image charge in the center of the sphere, because a charged sphere acts like a point-charge in it's center. So I can replace the sphere with a single point-charge.

Then I added a second image charge inside the wall with opposite charge [tex]-Q[/tex]. This second charged is placed exactly symmetrical to the first image charge.

So... if the first charge is placed by [tex]z=a[/tex], I have placed the second at [tex]z=-a[/tex].

Is this a correct/possible solution for this problem? Or do I need some different approaches here, because the wall has an effect on the charge on the sphere?

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Method of image charges

**Physics Forums | Science Articles, Homework Help, Discussion**