The Main Laws of the Refraction of Light

Have you ever got curious about a certain thing that makes you question the science and its processes? Like, while you see a straw emerged in a glass of water, it seems to bend in angles other than 90 degrees. This made us wonder as a small kid, but now that we are sensible to understand the scientific processes that make this happen. The process that leads to this bending is known as refraction. As per laws of refraction, this happens because when a ray of light moves from a denser to a rarer medium, it bends against the normal. Another factor that backs this process is the speed of light. The speed of light in air and that in the glass has different wavelengths that make it bend. 

Important Laws of Refraction 

  • Refraction is the process of change in the speed of light while entering from one transparent medium to another one.
  • If the ray of light passes through rarer to a denser medium, the refracted ray is closed to the normal. 
  • While if the ray of light passes through denser to a rarer medium, the refracted ray is away from the normal. 
  • According to the law of the refraction of light, “The incident ray, refracted ray, and the normal to the interface of the two transparent media at the point of incidence, all lie in the same plane.”
  • An incident ray passing through the normal always goes straight. 
  • As per the Snell’s Law of Refraction, the ratio of the sin of the angle of incidence to the sin of the angle of refraction is a constant, for the light of a given color and the given pair of media.
  • The constant derived in the laws of refraction is known as a refractive index.
  • Refractive Index indicates the relation of the physical quantities with the relative speed of the propagation of light.

Refraction Through a Rectangular Glass Slab

To understand the laws of refraction better, here is the phenomenon of refraction for the light passing through a rectangular slab. 

  • The first step is to take a white sheet and put a glass slab over it
  • Then, outline the slab and mark the four corners as point ABCD
  • Now, take two pins and mark two other points as E and F, which is at an edge with the points A and B
  • Stand at the opposite points and put a glance on the images of the pins E and F
  • Now, place two more pins G and H and see to it whether G, H, and E, F are in a straight line
  • Gently remove the pins and the slab
  • Join the points E and F and extend it up to AB. Now make EF meet at O. 

Similarly, join points G and H and extend it up to CD. Now make HG meet CD

  • Join O and O’ and extend EF till P