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Dielectric constant distribution![]() | This animation shows the propagation of an electromagnetic wave in a vacuum (refractive index and dielectric constant both 1). The wave travels in a straight line, and the flow of energy is characterized by the Poynting vector, which has the units W m-2. It is defined as S=E×B/μ0, where E is the electric field vector, B is the magnetic field vector, μ0 is the magnetic constant and "×" denotes the cross product. Wikipedia link: Poynting vector |
Electric field animation![]() | Time-averaged Poynting vector![]() |
This is an animation of the component of the electric field out of the plane of the page. | The direction in which energy is travelling at any instant is proportional to the cross product of the electric and magnetic fields, known as the Poynting vector. The arrows show the direction of the Poynting vector averaged over the simulation, while the colours show its strength. |