Write the essential conditions for total internal reflection to take place. Find the
expression relating critical angle with refractive index of denser medium.
Answers
Answer:
When light travels into a different medium, the speed of the light changes and the light is refracted (see The features of waves).
When light travels from a denser medium, eg glass, to a less dense medium, eg air, the speed of the light increases and the light refracts away from the normal. The angle of refraction is greater than the angle of incidence.
The diagram below shows the light refracting from glass into air.As the angle of incidence is increased, the angle of refraction also increases. At a certain angle of incidence, the light will refract 90 degrees and travel along the boundary between the two media. This angle of incidence is called the critical angle. The critical angle varies for different materials, but it is useful to know that it is around 42 degrees for glass. You will be reminded of this fact in the exam. The diagram below shows light hitting the glass-air boundary at an angle that is equal to the critical angle.
Explanation:
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