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Question
State one factor on which a critical angle for a given pair of media depends. The critical angle for the glass-air interface is 45° for the yellow light. Will it be equal to, less than or greater than 45° for (i) red light, (ii) blue light?
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Solution
The value of the critical angle for a given pair of media depends on the colour of light.
(Hint: Remember VIBGYOUR Violet has minimum ic whereas Red has maximum).
(i) For red light, the critical angle will be greater than 45°.
(ii) For blue light, the critical angle will be less than 45 °.
RELATED QUESTIONS
A ray of light travels from water to air as shown in the diagram given below :
1) Copy the diagram and complete the path of the way. Given the critical angle for water is 48°.
2) State the condition so that internal reflection occurs in the above diagram.
Angle of deviation is the angle which the ______ ray makes with the direction of ______ray.
What is total internal reflection?
Write the necessary conditions for the phenomenon of total internal reflection to
occur ?
Make the correct choices for each of the following :
Total Internal reflection takes place when
(where ∠i = angle of incidence, ∠r = angle of refraction, ∠C = critical angle)
A ray of light incident at an angle of incidence ‘i’ passes through an equilateral glass prism such that the refracted ray inside the prism is parallel to its base and emerges from the prism at an angle of emergence ‘e’.
What can you say about the value of the angle of deviation in such a situation?
The diagram shows a point source P inside a water container. Three rays A, B, and C starting from P are shown up to the water surface. Show in the diagram the path of these rays after striking the water surface. The critical angle for the water-air pair is 48°.
A ray of light passes through a right-angled prism as shown in the figure. State the angles of incidence at the faces AC and BC.
- Assertion (A): Propagation of light through an optical fibre is due to total internal reflection taking place at the core-cladding interface.
- Reason (R): Refractive index of the material of the cladding of the optical fibre is greater than that of the core.
Total internal reflection is defined as the complete reflection of light back into an optically denser medium when:
