ABSTRACT
The optical activity can occur in isotropic materials and cubic crystals, and is applicable to light passing along the optic axes in less symmetrical optical crystals. Coefficients for the Hall effect are independent of direction for isotropic materials and for all cubic crystals. If optical activity is present these plane-polarised waves can themselves be broken down into circular components whose refractive indices are modified from the mean values giving rise to the wavevector sheets. The tensor which is used to represent optical activity is called the gyration tensor. Using symmetry arguments, the number of possible components is increased compared with a third-rank tensor. It becomes difficult to measure the coefficients independently and the subject becomes somewhat specialised. The presence of the magnetic field produces a force on the moving charges within the conductor and initially there is a build-up of charge on the side faces of the conductor.
