The rotation of the plane of polarization of an electromagnetic wave as it passes through a region containing free electrons and a magnetic field; also known as Faraday rotation. The amount of rotation, in radians, is given by RMλ2, where RM is the rotation measure of the source and λ is the wavelength. Observation of the Faraday effect in pulsars is the most important means of determining the magnetic field of the Galaxy. It is named after the English physicist Michael Faraday (1791–1867).
Subjects: Astronomy and Astrophysics — Chemistry.