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Couple Moment and its Application Refractive Index and Its types

Refractive Index and Its types
2023-02-04 18:28:50

Refractive Index and Its types

In order to get the idea about the refractive index and its types, we need to understand about the refraction of the light. In this article, we are going to understand the refraction of light then we will discuss about the refractive index and the types of refractive index very briefly. We will also discuss the applications of each type of refractive index.

Refraction of Light

Sometimes, it seems or is observed that as light rays move obliquely from one media to another, the path or orientation of the light's propagation in the second medium alters in some way. When light moves from one medium to another, its velocity or speed changes, and this is explained in very simple terms. The speed of the medium we utilise and the characteristics of the other medium where the light originates determine how light is refracted. Additionally, this refraction phenomenon abides by specific laws. Refraction is caused by the visible modification in the speed or velocity of light beams.

Refractive Index

First of all, refractive index is a dimensionless quantity. Refractive index, the index of refraction, also referred to as, describes how quickly light passes through a substance. The refractive index gives details on the light's speed as it travels through various materials.The amount of shift in direction of light rays is what we refer to and compute as the refractive index whenever light that tends to flow obliquely from one medium to another alters its direction while passing from another medium. The refractive index is determined by comparing the speeds of light in various mediums.

The two media that light is going through determine the sort of refractive index. One of the materials that make up the absolute refractive index is vacuum, where the speed of light is 3.00 x 108 m/s. (exactly 299,792,458 meters per second.) The relative change in pace or velocity of light as it travels from one medium to another is known as the relative refractive index.

When moving from a rarer to a denser media, light rays tend to bend in the direction of the normal, whereas when moving from a denser to a rarer medium, they bend in the opposite direction.

Refractive index is of two types:

  • Absolute Refractive Index
  • Relative Refractive Index

Now we are going to understand briefly about all the two types of refractive index:

Absolute Refractive Index

The refractive index is measured or assumed to be the ratio of the velocity of light in a vacuum (c) to the speed of light in the material medium on which it falls (v) for a certain material medium. Small n is used to express or denote a medium's index of refraction, which is determined by the formula below:

n = C/V

Where V is the speed of the light in the given medium, and C is the speed of the light in the vacuum.

The speed of light in a vacuum is 3.00 x 108 m /s, which is its speed. With a small difference, it moves at about the same speed in air as it does in a vacuum. Therefore, the speed is only assumed to be 3.00 x 108 m /s while moving from the air to the medium. The absolute refractive index, as its name implies, provides us with an approximation of the optical density of the substance.

When compared to a material with a low index of refraction, which turns into a rarer medium, the one that has a higher refracted index becomes optically denser.Since they are two distinct numbers, a substance with a higher optical density does not necessarily have a higher mass by volume density. Kerosene, for example, does have a lower density than water but is optically denser because it has a higher refractive index (1.44 vs. 1.33), which indicates that it is visually denser than water.

Applications of Absolute Refractive Index

  • Gives us a general understanding of the absolute refractive index of a variety of material media besides vacuum and air, which we can use for carrying out laboratory tasks.
  • Is employed in the manufacturing of specific compounds using materials of known refractive indices.
  • They are utilized in the pharmaceutical industry to give a ballpark approximation of the compounds' optical density.
  • Absolute refractive index values are frequently used to distinguish between optically rarer and denser materials.

Relative Refractive Index

The speed of light when it transitions between media is described by the relative refractive index. As light exits one medium and enters another, its rate of speed changes. The relative refractive index is the name given to this variation in refractive index.

Applications of Relative Refractive Index

  • It is frequently employed to determine a substance's identity, verify its purity, or gauge a specific concentration.
  • It is typically and frequently used to determine the solute concentration in an aqueous solution. For instance, the refractive index of a sugar solution can be used to estimate its sugar content.
  • In the pharma or pharmacy sector, it is also used to determine the medication concentration.
  • It is frequently used to determine the dispersive power of prisms and the concentrating power of various lenses.
  • Additionally, it is frequently used to estimate the thermophysical characteristics of various hydrocarbons and petroleum blends.