- Question Answer
- State the laws of refraction of light. Explain the term absolute refractive index of a medium and
. State the laws of refraction of light. Explain the term absolute refractive index of a medium and
write an expression to relate it with the speed of light in vacuum
Ans. Laws of Refraction:
(i) The first law of refraction of light states that the incident ray, the refracted ray and the normal at the point of incidence, all lie in the same plane
(ii) The second law of refraction of light is the Snell's Law of Refraction. It states that the ratio of sine of the angle of incidence to the sine of angle of refraction is a constant for a given pair of medium.
sin i /sin r = constant
This constant (n) is called refractive index of the medium.
i. When the light is going from vacuum to another medium, then the value of refractive index is called the absolute refractive index.
ii.The ratio of speed of light in vacuum to the speed of light in a medium is called the absolute refractive index of that medium, i.e.,
Absolute refractive index (of a medium) = Speed of llight in vaccum (c) / Speed of light in medium (v)