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Refraction through Prism – A Question

A light ray falls perpendicular to one of the faces of a glass prism of angle 60 and refractive index 1.5,
Find;
a) the angle of emergence.
b) the angle of deviation.
Answer:
The question implies that the angle of incidence is 0
The ray will enter without any deviation. Therefore, the angle of incidence at the second face inside the prism = 60 degree
(From A +90+ (90-r2)=180)
Since the critical angle for glass is less than this, the ray of light will undergo total internal reflection. So it reflects towards the base internally.

Solving problems from kinematics and friction

I just want to know how to easily solve problems related to kinematics and friction. I don’t know why i always face problem in these two topics a lot……
Please help and tell some tricks to solve these both…….
THANK U

Dispersion

Ashish Asks:

IN  A PRISM DISPERSION OCCURS BUT NOT IN A GLASS SLAB PLEASE EXPLAIN ME CLEARLY WHY IN THE GLASS SLAB THE DISPERSION DOES NOT TAKES PLACE.

 

Answer: In a glass slab, the opposite sides are parallel. Though splitting up of light takes place inside the glass slab, the emergent rays are parallel to each other and enter simultaneously without any angular separation. But, in the case of a glass prism, the angular separation produced to the component colours  due to refraction at the first face is further enhanced at the second face. Thus the angular separation between the emergent colours enables the viewer to see the colours separately and thus the dispersion is observed.

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