Question

Tracing the light ray in a glass slab, which of the following quantities can be evaluated :
(A) Frequency of light wave
(B) Refractive index of slab
(C) Density of glass slab
(D) Component of light wave

Answer 1

Hint: When a light ray travels from air to a medium like glass slab, it gets refracted. Tracing this light we can find the value of the index of refraction commonly known as refractive index .

Complete answer:
A light ray travelling through air falls on a glass slab faces refraction because of different speed of light in different mediums . We perform an experiment and trace the path of the light to find the refractive index of the glass slab. The refractive index of air is taken to be unity.
Using glass slab, we can find the “index of refraction” or “ refractive index” of slab by drawing a trace of path . In this experiment, to trace the path of a ray of light through a parallel sided glass slab , we measure the angle of refraction for at least three different angles of incidence .
The angle of refraction can be equal , smaller or greater than the angle of incidence depending on the refractive index of the glass slab .

Using Snell's law we will quantise the refractive index.
It says that:
 $
  \dfrac{{\sin i}}{{\sin r}} = const \\
  \dfrac{{\sin i}}{{\sin r}} = n \\
 $

The value of this constant is “refractive index” .

Note: As the medium changes, the speed of light also changes and that is why the ray gets refracted either towards the normal or away from the normal. The ratio of the sine of angle of incidence to the sine of angle of refraction is constant and that constant is refractive index.