Electromagnetic metamaterials with a negative value for this property have been constructed, which m
Electromagnetic metamaterials with a negative value for this property have been constructed, which may see use in optically imaging things that are smaller than the diffraction limit. One is subtracted from this quantity in the Lensmaker's equation. When this quantity is polarization-dependent, as in calcite, a "double" type of this phenomenon may occur, called birefringence. This quantity measures how much slower light becomes in a medium. At an interface, Snell's law relates the angles of incidence to these quantities. For 10 points, name this dimensionless property of a medium that measures how much a ray of light is bent when it enters that medium. 
Electromagnetic metamaterials with a negative value for this property have been constructed, which may see use in optically imaging things that are smaller than the diffraction limit.
index of refraction [or refractive index] 