The optical propertiies of a medium are governed by the relative permitivity `(epsilon_r)` and relative permeability `(mu_r)`. The refractive index is defined as `sqrt(mu_repsilon_r)=n`. For ordinary material `epsilon_r>0` and `mu_r>0` and the positive sign is taken for the square root. In 1964, Russian scientist V. Veselago postulted the existence of material with `epsilon_r<0` and `mu_r<0`. since then such 'metamaterials' have been produced in the laboratories and thier optical properties sutdies. for such materials `n=-sqrt(mu_repsilon_r)`. As light enters a medium of such refractive index the phases travel away from the direction of propagation.
According to teh description above show that if rays of light enter such a medium from air (refractive index=1) at an angle `theta` in `2^nd` quadrant, then the refracted beam is in the 3rd quadrant.