The magnetic form of this phenomenon was discovered by Voight in 1902, who observed it in light propagating through a vapor. 
The magnetic form of this phenomenon was discovered by Voight in 1902, who observed it in light propagating through a vapor. Celophane is a cheap example of a material that exhibits it, and an eponymous effect, in which refraction varies as the square of the electric field, exploits this phenomenon in such applications as high-speed camera shutters. In general, it arises in the cases when the rank-2 dielectric tensor is real and symmetric, with three eigenvalues along the orthongal polarizatoin axes. Demonstrated by the Kerr effect, FTP, identify this electro-optical phenomenon, in which a material exhibits different refractive indices for light polarized in the plane of the field and light polarized normal to it.
The magnetic form of this phenomenon was discovered by Voight in 1902, who observed it in light propagating through a vapor.
birefringence (or double refraction)