Physics Asked by Fasi on April 19, 2021
I have been trying to solve the following question:
The potential on the surface of a sphere is given by
$mathbf {V = V_{0} sin^2theta sin2phi,;}$
find the potential outside the sphere
I am trying to solve it by separation of variable in spherical coordinates by using the following formula for potential outside the sphere,
$$V=sum_{l=0}^inftyfrac{B_{lm}}{r^{l+1}} {Y_l}^m (theta,phi)$$
Now the potential on the surface of the sphere is given, so we can use that for r=R as,
$$tag{1}V_{0}sin^2thetasin 2phi=sum_{l=0}^inftyfrac{B_{lm}}{R^{l+1}} {Y_l}^m (theta,phi)$$
Next for the value of $B_l$ I multiply both side with ${Y^*_l}^m$ and integrate. RHS becomes $frac{B_{lm}}{r^{l+1}}$ while LHS becomes interesting. I note that $sin^2theta$ $sin 2phi$ can be converted into $Y_2^2$ with some Constant factor. $Y_2^2$ is given as follows: $$ Y_2^2= A sin^2theta e^{imphi}$$
So my problem is, can I some how convert this into $Y_2^2$ so that it simply gives me the left hand side of equation ${(1)}?;$ I see that $sin2phi$ is the imaginary part of $e^{imphi}$ with $m=2$. Please guide me through this.
What if you assume that the initial potential has its imaginary component, just for the sake of the argument Vo $sin^2theta$ $sin 2phi$ = Re{$U_0Y_2^2$} where $U_0$ is some constant you get from the definition of your potential and $Y_2^2$? Then you indeed can prove that the potential outside the sphere is the same $Y_2^2$ with some constant factor. The imaginary part has no physical meaning then, you use only the real one since all equations must hold if you apply Re{} or Im{} to them. My guess you will come to something like C$cdot$Vo $sin^2theta$ $sin 2phi / r^3$
Spherical harmonics are orthonormal. If you have a spherical harmonic on one side, you have to have the same one on the other, no more and no less.
Answered by Philipp Oleynik on April 19, 2021
Get help from others!
Recent Answers
Recent Questions
© 2024 TransWikia.com. All rights reserved. Sites we Love: PCI Database, UKBizDB, Menu Kuliner, Sharing RPP