JEE Main & Advanced Physics Ray Optics Refraction of Light

The bending of the ray of light passing from one medium to the other medium is called refraction.

(1) The refraction of light takes place on going from one medium to another because the speed of light is different in the two media.

(2) Greater the difference in the speeds of light in the two media, greater will be the amount of refraction.

(3) A medium in which the speed of light is more is known as optically rarer medium and a medium is which the speed of light is less, is known as optically denser medium.

(4) When a ray of light goes from a rarer medium to a denser medium, it bends towards the normal.

(5) When a ray of light goes from a denser medium to a rarer medium, it bends away from the normal.

(6) Snell's law : The ratio of sine of the angle of incidence to the angle of refraction (r) is a constant called refractive index

i.e. \[\frac{\text{sin }i}{\text{sin }r}=\mu \] (a constant). For two media, Snell's law can be written as \[_{1}{{\mu }_{2}}=\frac{{{\mu }_{2}}}{{{\mu }_{1}}}=\frac{\sin i}{\sin r}\]

\[\Rightarrow \]\[{{\mu }_{1}}\times \sin i={{\mu }_{2}}\times \sin r\] i.e. \[\mu \sin \theta =\] constant

Also in vector form : \[\hat{i}\times \hat{n}=\mu \,\mathbf{(}\hat{r}\times \hat{n}\mathbf{)}\]