Refraction of Light

Refraction is an observational phenomenon that occurs with a ray of light. In simple terms, it is called the bending of light rays when they go from a single transparent substance to another transparent substance. 

Refraction happens with several things around us, including eyeglasses, lenses, water, sound, and other waves. This bending results in the phenomenon of the refraction of light. Hence, we can have objects like spectacles, glasses, prisms, rainbows, and lenses. 

Refraction 

Refraction is the bending of a wave when it enters a medium where its speed is different. The refraction of light occurs on light passing from a fast medium to a slow medium or a slow medium to fast. This always bends the ray of light away from the normal, and in the latter case, to the edge of the two given mediums.

Due to the presence of no medium, the speed of light rays is maximum in a vacuum. In any medium, the light will travel slowly compared to a vacuum. This interaction leads to the change in the direction of light at the edges of two separate mediums. The frequency at which the incident light moves is always constant, but wavelength and speed change. As a ray of light enters a more dense medium than the previous medium, it tends to bend towards the normal line, whereas whenever a scarce/light medium is there, the ray shifts far from the normal.

Laws of refraction

The two laws of refraction are as follows:

• The three rays, namely the refracted ray, the normal, and the incident to the surface refracting, come along the same plane

• Snell’s law: Snell’s law states that the sine ratio of the angle between the incident ray and the normal (angle of incidence) to the sine of the angle between the refracted ray and the normal (angle of refraction) remains constant. The constant depends on the refractive index of two media and the wavelength of the incident light

Refractive index

Let the angle of incidence be θᵢ and the angle of refraction be θᵣ at the interference of two different media, according to Snell’s law of refraction, sinisinr = μ = Constant. This constant represented by μ is called the relative refractive index of another given medium with respect to the first medium. Given that the first medium is taken as vacuum, μ is referred to as the absolute refractive index.

Types of refraction

Refraction from rarer to denser medium: In such cases, the second medium is rarer than the first medium. Henceforth in all these cases, the ratio of refractive index of the first medium to the other mediums is always greater than 1. The angle of refraction is also smaller than the angle of incidence. I.e., the refracted ray shifts towards the normal.  

Refraction from denser to rarer medium: In this case, the relative refractive index of the first medium with respect to the second is lesser than 1. The angle made at refraction by the light ray is also less than the angle of refraction after the ray passes the normal. i.e., the refracted ray shifts away from the normal.

Conclusion

Refraction is another phenomenon that occurs with the ray of light. In simple terms, it is called the bending of light rays when it goes from a single transparent substance to another transparent substance. This bending results in the phenomenon of refraction of light. Hence, we are able to have objects like spectacles, glasses, prisms, rainbows, and lenses. The refraction of light occurs on the passing of light from a fast medium to a slow medium or a slow medium to fast. This always bends the ray of light away from the normal, and in the second case, to the edge of the two given mediums.