Name: Total Internal Reflection From Prism
Uploaded: 2019-07-19
Duration: 1 min 56 s
Description: You must have seen reflectors on a bicycle. Why are they attached to the mudguards? What use do they have? Let’s watch this video on reflectors to find out.

Question

A ray of light falls normally on a rectangular glass slab. Draw a ray diagram showing the path of the ray till it emerges out of the slab.

Accepted Answer

When a ray of light passes from rarer to denser medium it bends towards the normal, thereby making an angle of refraction which will be smaller than the angle of incidence. In the case where the ray of light falls normally of the rectangular glass slab then it passes through it without bending, in a straight line as the angle of incidence is zero in this condition.

This can be proved by Snell's law, according to which $\frac{S i n i}{S i n r} = n$ .

$S i n i = n S i n r$

$\frac{S i n i}{n} = S i n r$

The angle between the incident ray and the refracted ray is $0 °$ , and $\sin 0 ° = 0$ therefore, angle of refraction will also be $0 °$ .

A ray of light falls normally on a rectangular glass slab. Draw a ray diagram showing the path of the ray till it emerges out of the slab.

Important Questions on Refraction at Plane Surfaces

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