The differential form of Maxwell’s equations are solved numerically using a time marching finite difference scheme inside all the Yee grid cells. The following illustration shows the field components in the Yee grid.
[[File:fdtd1_tn.png]] Figure 1: |thumb|300px|The Yee cell geometry and definition of the electric and magnetic field components.]]
For example, Maxwell’s equations for an isotropic, time-invariant and homogeneous medium without electric or magnetic losses are given by: