Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Ray Optics

Question:

Case: Read the following passage and answer accordingly

Total internal reflection is the phenomenon of the reflection of light into a denser medium at the interface of a denser medium with the rarer medium. For this phenomenon to occur necessary condition is that light must move from denser to rarer and the angle of incidence in the denser medium must be greater than the critical angle for the pair of media in contact. Critical angle depends on the nature of the medium and wavelength of light. We can show that µ=1/sinC (where C is the critical angle).

The critical angle for air-water interface for violet colour is 49°. Its value for red colour will be;

Options:

49°

Higher than 49°

Lower than 49°

Cannot say

Correct Answer:

Higher than 49°

Explanation:

Critical angle is minimum for violet and maximum for red. Red light has lower refractive index than yellow light hence it's critical angle will be higher than violet light.