EXPLANATION:
- Mathematically the refractive index can be written as
⇒‌ Speed of light in a medium ‌(v)=‌| ‌ Speed of light in vaccum(C) ‌ |
| ‌ Refractive index ‌(µ) |
- As the speed of light in a vacuum is constant, therefore we can say that speed of light in a medium is inversely proportional to the refractive index of the medium.
- Hence, we can say that the speed of light travels at different speeds in different media. Therefore option 1 is correct.
- The speed of light in the air is
3×108m∕s. Therefore option 2 is correct.
- When the light is traveling from water to air and as we know that the refractive index of water
(1.33) and that of air (1.008), it means the water is a denser medium and air is a rarer medium.
- Whenever light goes from water to air, the frequency of light and phase of light does not change.
- However, the velocity of light and wavelength of light change (increases) because the light is traveling from denser medium
(µ‌water ‌=1.33) to rarer medium
(µ‌air ‌=1.008). Therefore option 3 is incorrect.