This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “Nicol Prism”.
1. The working of Nicole prism is based on the phenomenon of ____________
d) Double Refraction
Explanation: The working of Nicol Prism is based on the phenomenon of Double Refraction. When a beam of unpolarized light passes through a doubly refracting crystal such as calcite, it splits into two plane-polarized beams.
2. In the O-ray is eliminated by ____________
b) Total internal reflection
Explanation: In a Nicol Prism, the O-ray is eliminated by total internal reflection while the E-ray is transmitted through the Nicol Prism. Thus, a plane polarized light with vibrations in the principal section of the crystal is obtained.
3. In the Nicol Prism experiment, the calcite crystal length is x times its breadth. What is x?
Explanation: In this experiment, a calcite crystal whose length is three times its breadth is taken. The calcite crystal is the doubly refracting crystal that splits the unpolarized light into two plane-polarized beams.
4. For E-ray, the Canada balsam layer is optically rarer.
Explanation: Canada Balsam is a transparent substance, whose refractive index lies between the refractive indices of O-ray and E-ray. Thus, for an E-ray, it is optically denser while for an O-ray it is optically rarer.
5. The critical angle for O-ray with respect to Canada balsam is ___________
Explanation: We know Canada balsam is optically denser than calcite for O-ray. The refractive index for O-ray is 1.069 while the critical angle turns out to be 69°.
6. The prism does not act as a polarizer when _____________
a) The angle of incidence is less than the critical angle for the O-ray
b) The angle of incidence is greater than the critical angle for the O-ray
c) The angle of incidence is less than the critical angle for the E-ray
d) The angle of incidence is greater than the critical angle for the E-ray
Explanation: If the angle of incidence is less than the critical angle for the O-ray, it is not reflected and is transmitted through the prism and so the prism does not act as a polarizer.
7. Nicol Prism can act as a polarizer as well as an analyzer.
Explanation: Nicol Prism can be used as a Polarizer as well as an analyzer. Thus, it can polarize an unpolarized light and also detect a plane-polarized light.
8. What should be the maximum angle between the extreme rays of the incident beam for the Nicol prism to work perfectly as a polarizer?
Explanation: The angle between the extreme rays of the incident beam should be less than 28o so as to avoid the total internal reflection of E-ray and the transmission of O-ray.
Explanation: In the figure, two Nicol Prisms are placed together. One acts as a polarizer while the other acts as an analyzer. This combination is called Polariscope.
10. In polariscope, if the two prisms are crossed, what would be the intensity of the transmitted polarized beam?
b) 2 Io
c) 1/2 Io
Explanation: As the two prisms are crossed, the angle between the principal sections of the two prisms would be 90°. Thus, according to Malus law, the intensity of the transmitted bean would be zero. Thus, no light would come out.
Sanfoundry Global Education & Learning Series – Engineering Physics.
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