A potential distribution through a slit in a thick conducting plane is examined. The Pourier-transform is used to represent the potential in the spectral domain and the boundary conditions are enforced to represent a solution in closed form. Our solution is in a rapidly converging series so that it is numerically efficient. The Fourier-transform approach is novel in that it allows us to obtain a simple series solution without recourse to the Schwarz-Christoffel transformation.