Maxwell's equations

Maxwell's equations were a series of equations used in classical electrodynamics.

A version of these equations were written on a table in one of the habitation hubs of Sanctuary Base 6. (TV: The Impossible Planet)

Behind the scenes
Maxwell's equations are named for James Clerk Maxwell, whom the Fifth Doctor once identified as a friend. (AUDIO: The Haunting of Thomas Brewster)

The version of these equations given in the episode are in their differential form. The variables, vectors and operators written include $$D$$ (the electric displacement field), $$\rho$$ (the free electric charge density) , $$B$$ (the magnetic field in Teslas) , $$H$$ (the magnetic field in $$\frac{Amperes}{m^{2}}$$ ) , and $$\nabla$$ (the differential operator). In addition, the fourth equation may or may not include Maxwell's Correction, and thus include $$J_{f}$$ (the free current density), all shots shown of these equations in the episode are from an angle and distance that make it impossible to tell.