Sphere Sources, Ideal Three-Dimensional Models

2 Sphere Sources, Ideal Three-Dimensional Models 

The monopolar sphere is the most basic geometry in the sense that any electrode in an infinite homogeneous medium reverts to a symmetrical spherical geometry at 

The spherical coordinate system with the coordinates r, 0, and (p is of course well suited for spherical sources. A sphere in a homogeneous medium disperses the current radially out in all directions. Because the surface area of a sphere is 4Tcr, the current density falls proportional to r. As we shall see, this is in contrast to a line source where the current density falls proportional to r (Table 6.1). Because the current spreads out in all directions, a fliree-dimensional (3D) analysis is necessary, but in a homogeneous medium any plane through the sphere center will show the same two-dimensional (2D) plot. 

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