- #1
Gregg
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Homework Statement
## \frac{\partial^2 V}{\partial x^2} +\frac{\partial^2 V}{\partial y^2} = 0 ##
it's defined for ##V=0 ## for
## x=0, 0<y<b##,
## x=a, 0<y<b##,
## y=0, 0<x<a##
##V=V_0 x/a ## for ## y=b, 0<x<a##
Homework Equations
None.
The Attempt at a Solution
I've got
##V(x,b) = \displaystyle V_0 x/a = \sum_{n=1}^{\infty} K_n \sin ({n \pi x \over a}) \sinh ({n \pi b \over a}) ##
At first I thought I could set K to 0 for n>1 and do a simple division, but I don't know what K1 is. Do I always need to find Fourier coefficients. I have seen a problem www.robots.ox.ac.uk/~jmb/lectures/pdelecture5.pdf here where in the final stage they do something like this. I'm guessing I need to do the former, but I am interested to know if the other method is possible.
As for the coefficients, the function is odd so the only integral I need is the sine integral.
## K_n = \frac{1}{a} \int_0^{2a} \frac{V x}{a} \sin ({n \pi x \over a}) dx =-\frac{2V}{n\pi} ##
I think this is right:
##V(x,y) = \sum_{n=1}^{\infty} -\frac{2V}{n\pi} \sin ({n \pi x \over a}) \sinh ({n \pi y \over a})##
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