Most materials have the refractive index, `n gt 1`. So, when a light ray from air enters a naturally occuring material, then by Snell's law, `(sin theta_(1))/(sin theta_(2)) = (n_(1))/(n_(2))`, it is understood that the refracted ray bends towards the normal. But it never emerges on the same side of the normal as the incident ray. According to electromagnetism, the refractive index of the medium is given by the relation, `n = (c // v) = +- sqrt(epsilon_(r ), mu_(r ))`, where `c` is the speed of the electromagnetic waves in vacuum, `v` its speed in the medium, `epsilon_( r)` and `mu_( r)` are negative, one must choose the negative root of `n`. Such negative refractive index materials can now be artifically prepared and are called meta-materials. They exhibit significantly different optical behaviour, without violating any physical laws. Since `n` is negative, it results in a change in the direction of propagation of the refracted light. However, similar to normal materials, the frequency of light remains unchanged upon refraction even in meta-materials.
Answer the following questions :
For light incident from air on a meta-material, the appropriate ray diagram is

Options

A.
B.
C.
D.

Answer

c

Explanation

Metamaterial has a negative refractive index.
`:. sin theta_(2) = (n_(1))/(n_(2)) sin theta_(1) implies n_(2)` is negative.
`:. theta_(2)` is negative.