119
edits
Changes
Jump to navigation
Jump to search
Line 67:
Line 67: + + + +
Describe equation #2
Now D = <math>\epsilon\ E</math> in the straightforward case (more about that later), so
Now D = <math>\epsilon\ E</math> in the straightforward case (more about that later), so
:<math>\nabla \cdot \mathbf{D} = \rho</math>
:<math>\nabla \cdot \mathbf{D} = \rho</math>
===Absence of Magnetic Monopoles===
The second of the equations is just like the first, but for the magnetic field. The divergence of B must be the spatial density of magnetic monopoles. Since they have never been observed (though various Grand Unified Theories might allow for them), the value is zero.
This wasn't formulated initially in terms of monopoles, but was actually a statement that magnetic "lines of force" (the lines that intuitively describe the field) never end. They just circulate around various conductors carrying electric current. In contrast to this, lines of the electric field can be thought to "begin" and "end" on charged particles.
==Other Formulations==
==Other Formulations==