Maxwell's equations. Maxwell's equations are a set of partial differential equations that, together with the Lorentz force law, form the foundation of classical electrodynamics, classical optics, and electric circuits.
These fields in turn underlie modern electrical and communications technologies. Maxwell's equations describe how electric and magnetic fields are generated and altered by each other and by charges and currents. They are named after the Scottish physicist and mathematician James Clerk Maxwell, who published an early form of those equations between 1861 and 1862. The equations have two major variants. The "microscopic" set of Maxwell's equations uses total charge and total current, including the complicated charges and currents in materials at the atomic scale; it has universal applicability but may be unfeasible to calculate.
Fresnel equations. Partial transmission and reflection amplitudes of a wave travelling from a low to high refractive index medium.
Overview[edit] The equations assume the interface is flat, planar, and homogeneous, and that the light is a plane wave. Lenz's law. Lenz's law /ˈlɛntsɨz lɔː/ is a common way of understanding how electromagnetic circuits obey Newton's third law and the conservation of energy.[1] Lenz's law is named after Heinrich Lenz, and it says: An induced electromotive force (emf) always gives rise to a current whose magnetic field opposes the original change in magnetic flux.
Lenz's law is shown with the negative sign in Faraday's law of induction: which indicates that the induced emf (ℰ) and the change in magnetic flux (∂ΦB) have opposite signs.[2]