Question

a glass slab of refraction index of NA is placed in a medium refraction index NB . make the diagram for path of light whrn NA<NB​

Answer 1

Answer:

In the case of a reflected ray, nA = nB = n2 = n1,

n1 Sinθ i = n1 Sinθ r, which is the same as Sinθ i = Sinθ r.

From this, it is easy to see that the angle of incidence and the angle of reflection are the same!

In the case of the transmitted, or refracted, ray,

n1 Sinθ i = n2 Sinθ t.

If n1<n2, then the angle of refraction is always smaller than the angle of incidence. If n1>n2, then the angle of refraction is larger than the angle of incidence…when there is an angle of refraction! Imagine the angle of incidence getting larger and larger for the case of n1>n2. Eventually the refracted ray will make an angle of 90° with the surface normal. If the angle of incidence is increased beyond that angle, then refraction does not occur! All of the light incident on the interface is reflected back into the incident medium! The smallest angle of incidence at which total internal reflection occurs is called the critical angle, qc. Using Snell’s law,

Explanation:

These diagrams illustrate two different cases of refraction. Total internal refraction is depicted in the sketch on the right.

Many devices take advantage of the total internal reflection, including optical waveguides (like optical fiber). A waveguide is a length of transparent material that is surrounded by material that has a lower index of refraction. Rays that intersect the interface between the waveguide material and the surrounding material at angles equal to or larger than the critical angle are trapped in the waveguide and travel losslessly along it.