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Question
Name two factors which affect the critical angle for a given pair of media. State how do the factors affect it.
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Solution
The factors which affect the critical angle are:
- Wavelength (colour) of light: Since a transparent medium's refractive index increases with violet light and decreases with red light, the critical angle for a pair of media increases with red light and decreases with violet light. Thus, the critical angle rises as the light's wavelength increases.
- The temperature: The critical angle for that pair of media increases as the temperature of the medium rises because its refractive index falls. As a result, the critical angle rises as the temperature rises.
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