question_answer

Refractive index of material is equal to tangent of polarising angle. It is called:

A)  Brewsters law 

B)  Lamberts law

C)  Malus law          

D)  Braggs law

Correct Answer: A

Solution :

(a) Brewsters law state that when ordinary light is incident on a transparent surface at polarising angle \[({{i}_{p}})\] for that surface, the tangent of angle of polarisation is equal to the refractive index \[(\mu )\] of the medium of surface that is (b) Lamberts law concerns to rate of absorption of radiation as it travels deeper into a medium. It states that the intensity \[I\] of transmitted radiation falls off exponentially with distance d in the medium.                 \[I={{I}_{0}}{{\exp }^{\alpha d}}\] (c) Law of malus states that the intensity of light coming out of analyser is proportional to the square of the cosine of the angle between the plane of analyser and polariser.                 \[I={{I}_{0}}{{\cos }^{2}}\theta \] (d) According to Braggs law, if a beam of \[X-\]rays of wavelength \[\lambda \] is directed at a crystal with parallel crystal planes that are distance d apart, then the reflected \[X-\]rays from each plane undergo interference.