The Refractive index is also known as the index of refraction. It helps us find out how the path of light is bent while it enters into the material from the vacuum. It is calculated as the ratio of the speed of light in a vacuum(3*10^8 m/s) to the speed of light in that material.
Meaning of refractive index
It is a ratio of the speed of light in a vacuum to the speed of light in a medium. It varies from one medium to another. It deals with two aspects:
- Speed of light in the medium
- The angle of refraction.
It is defined as the refractive index of a material is a dimensionless number that describes how fast the light travels through the material.
Formula of refractive index
N(refractive index) = c (speed of light) /v (phase velocity)
C is the speed of light in the vacuum.
V is the phase velocity of the light in the medium
The Refractive index determines how many paths of light are bent or else refracted when entering the material. It is described by snell’s law of refraction.
N1 sinθ1 = n2 sinθ2,
where θ1 and θ2 is the angle of incidence and refraction.
The Refractive index also determines the amount of light that is reflected when reaching the interface and as well as the critical angle for the total internal reflection, its intensity.
The Refractive index varies with wavelength, it causes white light to split into constitute colors when refracted. It is called dispersion. This effect is observed in prisms and rainbows ad chromatic aberration in lenses. The concept of a refractive index is applied across the full electromagnetic spectrum from X-rays to radio waves. It is also applied to the wave phenomenon like sound.
In such a case with speed, the speed of sound is used instead of light and the reference medium other than a vacuum must be chosen, because sound cannot travel through a vacuum.
Factors affecting refractive index:
- Type of material
- Wavelength of light
Examples of refractive index:
- Air ~1
- Water 1.33
- Diamond 2.417
Application of refractive index:
- Camera lenses to know how much light will change its path from the camera lens. It helps in the correction of the position of an object
- Contact lenses are calibrated according to each person’s eyesight.
- In liquids, there is a specific instrument that is used to calculate refraction occurring in the liquids.
- It is helpful when mixing two liquids in industries and while a certain type of candies.
- Spectacles
The Refractive index is also known as the index of refraction. It helps us find out how the path of light is bent while it enters the material from the vacuum. It is calculated as the ratio of the speed of light in a vacuum(3*10^8 m/s) to the speed of light in that material.
