Refraction through a prism

Introduction

Did you know that today’s scientists are on the verge of producing an invisibility cloak? You are mistaken if you believe this is magic. The goal of these researchers is to create a fabric that will entirely conceal items, at least in visible light. This is based on the theory of refraction through a glass prism, which is a very basic scientific principle.

Refraction of light through a prism occurs when light passes through a glass prism and refracts both entering and exiting the prism. The emergent and incident rays are not parallel to each other because the entry and exit (refracting surfaces) are not parallel to each other.

Though we’ve already had a brief idea of the refraction of light through a glass prism in class 10, we’ll here understand it more properly! 

What is Refraction?

The bending of light beams at the meeting point of two transparent media is known as refraction. This is due to a shift in the direction of the light wave as well as the bending of light waves at the media’s meeting point. Refraction of light happens when the speed of a light wave changes when it approaches a new surface, resulting in a change in direction or bending of the light wave.

Refractive Index

The refractive index is a metric that measures how far light rays bend when they enter another medium. The letter ‘n’ stands for refractive index.

‘n’ is a derived variable.

It’s the ratio of c and  v.

Where c is the velocity/speed of light in the air of a specific wavelength.

And v denotes the speed of light in any medium.

What is a Prism?

A prism is a solid geometric figure with equal and parallel rectilinear figures on all of its end sides. The sides of a prism are always parallelograms or rectangles. Prisms come in a variety of shapes, including triangles, squares, and rectangles. When used for refraction, prisms must be manufactured of transparent material. A prism’s sides must be at an acute angle (less than 90 degrees).

Let’s look at the refraction of light through a glass prism! 

Refraction Through a Prism

Consider the refraction through the prism diagram to understand the phenomena properly! 

Let’s assume the ABC prism, which is a glass triangle prism. Let BC be the starting point, and AB and AC be the refracting surfaces. The line OP represents the incident light ray. The incident ray is the light that enters the prism. The speed of the light ray changes as it approaches the new surface on the prism’s side, and it bends, forming a new beam within the prism, which is known as the refracted ray.

This refracted ray will be referred to as PQ. The refracted light ray then passes through the prism and emerges from the opposite side. Because it emerges from the surface, the light ray is referred to as an emergent ray.

QR is the designation given to the emerging ray in the diagram. Because of the shift in medium, the emergent ray QR bends at an angle from the refracted ray PQ.

When a ray of white light passes through a prism, it scatters into seven different colors. When white light is refracted, it breaks into its constituents due to the varying degrees of deviation experienced by different hues of light waves.

Phenomena caused by Refraction:

Many additional phenomena are caused by refraction.

• When looking at a straw dipped in a glass of water, the part in the air and the part in the water appear to be different straws! It appears to be warped.

• Travelers in the desert may mistakenly see water or trees on the ground when there is none. The term for this phenomenon is ‘mirage.’

• Some other natural phenomena, such as the twinkling of stars and the production of rainbows, are also caused by refraction.

• When sunlight passes through water droplets, it disperses into the seven hues that make up a rainbow. In truth, when light passes through a prism, rainbow-like things can form. When light passes through a prism, it might disperse due to the geometry of the prism. To understand this, consider how light refracts when it passes through a glass prism.

What happens in a prism?

The “Dispersion of light rays” is the main phenomenon that occurs in a prism. The main source of dispersion is a change in media. When a light beam changes medium, dispersion is the amount by which it is refracted depending on its frequency and wavelength. When a light ray passes through a prism, it is refracted and distributed into a band of seven colors known as VIBGYOR(Violet, indigo, blue,  green, yellow, orange, red) or the Rainbow colors when it emerges from the prism medium.

Key Points to Remember

• The refraction of light through a prism is a phenomenon in which light bends as it passes through different mediums.

• When light passes through a glass prism, it refracts both entering and exiting the prism.

• The refractive index is a metric that measures how far light rays bend when they enter another medium.

• A prism is a solid geometric form with equal and parallel rectilinear figures on all of its end sides.

• The “Dispersion of light rays” is the main phenomenon that occurs in a prism.

• The white light beam disperses, and when it reaches the other surface, it disperses, even more, resulting in the VIBGYOR rainbow colors.

Conclusion 

Hopefully, you’ve understood the refraction of light through a prism!

Here, we’ve learned about refraction through the prism, phenomena that cause refraction, how a rainbow is formed, and other key points. There’s no denying that the topic is vast and requires ample time to understand.