"Change in path of a light ray as it passes from one medium to an… - Vidyadip

Question

"Change in path of a light ray as it passes from one medium to another medium is called refraction of light."

When light travels from a rarer medium to a denser one, it bends towards the normal $(i>r)$ and when travels from a denser medium to a rarer one. it bends away from the normal $(iWhere, $\quad i=$ Angle of incidence
and $\quad r=$ Angle of refraction
We can see refraction in our daily life, some of the examples are given below :
The bottom of a tank or pond containing water appears to be raised due to refraction of light which takes place when light rays pass from the pool of water into the air. The letters appear to be raised when viewed through a glass slab placed over the document because of refraction of light.
When a light ray enters in a glass slab, then the emergent ray is parallel to the incident ray but it is shifted sideward slightly.
In this case, refraction takes place twice, first when ray enters glass slab from air and second when exits from glass slab to air.
(i) What do you mean by optically rarer and denser medium ?
(ii) What is the cause of refraction?
(iii) Draw a ray diagram shotving refraction through a glass slab.
or
(iv) Give one example of refraction from our daily life experience other than the two examples given above.

✓

Answer

(i) $\quad \Lambda$ medium in which the speed of light is more, is known as optically rarer medium and the medium in which speed of light is lesser is known as optically denser medium.
(ii) Speed of light is different in different media. It is lesser in denser medium and higher in rarer medium. So, when light enters a denser medium, its speed reduces and it bends towards the normal and when it enters rarer medium, its speed increases and it bends away from the normal
(iv) A lemon kept in water in a glass tumbler appears to be bigger than its actual size, when viewed from the sides.

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