Q18 / 237 · NTA Abhyas (NEET) 2020 · Physics · Ray Optics

A light ray moving in medium-I (of refractive index n1) is incident on interface of two media and it is totally internally reflected at the interface. Now, refractive index n2 of medium-II is decreased, then

Figure

  • A
    ray will move completely parallel to the interface
  • Correct answer
    B
    ray will be still totally internally reflected at interface
  • C
    ray will be totally transmitted into medium-II only, if angle of incidence is increased
  • D
    ray will be totally transmitted in medium-II

Solution

As n2 decreases, iC=sin-1⁡n2n1 also decreases.

So, condition i>iC 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 i>iC.

Hence, the correct answer is option: 'B'.

More Ray Optics Questions