The optical properties of a medium are governed by the relative permittivity (εr) and relative permeability (µr ). The refractive index is defined as √µr εr = n. For
ordinary material εr > 0 and µr > 0 and the positive sign is taken for the square root. In 1964, a Russian scientist V. Veselago postulated the existence of
material with εr < 0 and µr < 0. Since then such ‘metamaterials’ have been produced in the laboratories and their optical properties studied. For such materials
n = -√µrεr. As light enters a medium of such refractive index the phases travel away from the direction of propagation.
(i) According to the description above show that if rays of light enter such a medium from the air (refractive index =1) at an angle θ in 2nd quadrant, them the
refracted beam is in the 3rd quadrant
(ii) Prove that Snell’s law holds for such a medium
(1)
BC = √μrεr (CD-AE)
BC >0; CD > AE
-√μrεr AE = BC – √μrεr CD
BC = √μrεr (CD – AE)
AE > CD
Therefore, BC < 0
(ii) BC = AC sin θi
CD – AE = AC sin θr
BC = √μrεr
AC sin θi = √μrεr AC sin θr
sin θi/sin θr = √μrεr