Refraction At Spherical Surfaces And
Refraction at Spherical Surfaces

Laws of refraction:

Refraction describes how light bends when passing from one medium to another.

Refractive index(n):

The ratio of the speed of light in vacuum to its speed in a material is known as the refractive index of that material.

It is a dimensionless quantity.

Snell’s law:

Snell’s Law describes how light is refracted at the boundary between two media.

It is expressed as: $n_1 \sin \theta_i = n_2 \sin \theta_t$

Where $n_1$ and $n_2$ are the refractive indices of the two media and $\theta_i$ and $\theta_t$ are the angles of incidence and refraction.

Absolute Refractive Index:

The ratio of the speed of light in vacuum (c) to the speed of light in the medium (v) is known as the absolute refractive index.

Mathematically, it is represented as $$\eta=c/v$$

Relative Refractive Index:

It is the ratio of absolute refractive indices of two materials/media.

Mathematically, $$n_{21}=n_2/n_1$$ Where $$n_{21}$$ is the relative refractive index of medium 2 with respect to medium 1 and $n_2$, $n_1$ are the absolute refractive indices of medium 2 and medium 1 respectively.

Real and Apparent Depth:

The actual distance from an object to the surface is called real depth whereas apparent depth is the perceived distance from the object’s surface to its image.

Total Internal Reflection:

Total Internal Reflection (TIR) happens when light passes from a denser medium to a rarer one and the incident angle is greater than a certain critical angle.

This phenomenon is crucial in the working of optical fibers.

Critical Angle:

The angle of incidence for which the refracted angle becomes 90° is known as the critical angle.

It is the minimum angle of incidence required for total internal reflection.

Prism and Its Types:

A prism is a transparent optical element with flat, polished surfaces that refract light.

There are different types of prisms like triangular prisms, rectangular prisms, and more.

Prisms are used in a wide range of optical applications such as dispersion of light, spectroscopy, and image processing.

Dispersion of Light:

It occurs when light of different wavelengths (colors) is refracted at different angles, causing the light to spread out into a spectrum.

Prisms are commonly used to demonstrate this effect.

Rainbow:

A rainbow is a naturally occurring optical phenomenon that appears as a circular arc of distinct colors in the sky.

It is caused by the dispersion of sunlight as it passes through raindrops.