Q18 / 237 · NTA Abhyas (NEET) 2020 · Physics · Ray Optics
A light ray moving in medium-I (of refractive index ) is incident on interface of two media and it is totally internally reflected at the interface. Now, refractive index of medium-II is decreased, then


- Aray will move completely parallel to the interface
- Correct answerBray will be still totally internally reflected at interface
- Cray will be totally transmitted into medium-II only, if angle of incidence is increased
- Dray will be totally transmitted in medium-II
Solution
As decreases, also decreases.
So, condition is still satisfied and there will be still total internal reflection at interface. If angle of incidence is increased, then ray will be still totally internally reflected at interface because .
So, condition is still satisfied and there will be still total internal reflection at interface. If angle of incidence is increased, then ray will be still totally internally reflected at interface because .
Hence, the correct answer is option: 'B'.