The laws of refraction are:

  • The incident ray, the normal and the refracted ray all lie in the same plane.
  • The ray of light bends towards the normal when it passes from a rarer medium to a denser medium and away from the normal when it passes from the denser medium to the rarer medium.
  • If a ray of light travels normally ( i = 0), it goes straight.
Due to refraction of light, the light rays coming from the apparent position of the fish appears shorter eyes and he hits the spear at that point but the fish does not get hit because the actual position of the fish is slightly below that of apparent position of the fish.
The process of bending of light as it passes from one medium to another medium is called refraction of light.

AO → incident ray
OB → refracted ray
BC → emergent ray
MN and M'N' = normal
∠AOM = Angle of incidence
∠BON = Angle of refraction
The velocity of light in rarer medium is greater than velocity of the light in denser medium. So, because of the variation of speed of light in two medias, the light bends which is the main cause of refraction.
  1. A stick partly immersed in water and placed inclined to the surface, appears bent at the surface.
  2. A swimming pool appears shallower than it really is.
The laws of refraction are as follows:
  1. The incident ray, refracted ray and the normal lies in the same point of a plane.
  2. A ray of light bends towards the normal when it travels from rarer medium to denser medium and bends away from the normal when it travels from denser medium to rarer medium.
  3. The ratio of sine of angle of incidence (Sin i) to the sine of angle of refraction (sin r) is always constant for a given pair of media.
Mathematically,
= µ (constant)
The constant quantity 'µ' is called refractive index.
The refractive index of a medium is defined as the ratio of velocity light in air (or vacuum) to the velocity of the light in the medium.
∴ RI of a medium =
  1. The refraction of light is shown in the figure.
  2. In the given figure:
    AO → incident ray
    OB → refracted ray
    BC → emergent ray
    MN = normal
    ∠AOM = Angle of incidence
    ∠BON = Angle of refraction
  3. Since the refracted ray bends towards the normal, we can say light comes from the rarer medium (water) and falls to denser medium (glass).
  1. The refraction of light is shown in the figure.
  2. Due to refraction of light, the light ray coming from the parts of pipe inside the water gets bent at the surface of the water. These deviated rays appear on our eyes and the parts of ruler inside the water appear bent.