This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Lecture 7 Notes, 95.657 Electromagnetic Theory I, Fall 2011 Dr. Christopher S. Baird, UMass Lowell 1. Expansion of Green Functions in Spherical Coordinates- Consider the problem of a spherical boundary with radius a , the potential is known on the boundary, there is charge present, and we wish to find the the potential anywhere external to the sphere.- We have already solved this problem using Green's functions: x = 1 4 x ' G D d 3 x ' 1 4 d G D d n ' da ' External to a spherical boundary we have already found the Green's function, it being the potential created by a unit charge and its image: G x , x ' = 1 x x ' 1 x ' a x a x ' x ' - When solving problems with both charges and boundary surfaces, the mathematics is simplified if the Green's function is expanded in spherical harmonics.- The addition theorem was used to find the spherical harmonics expansion of a unit charge: 1 r r = 4 l = m = l l 1 2 l 1 r l r l 1 Y l m * ' , ' Y lm , if r r and 1 r r = 4 l = m = l l 1 2 l 1 r l r l 1 Y l m * ' , ' Y lm , if r r- Both the point charge and its image can be expanded in this way to give the spherical Green's...
View Full Document
- Fall '11