Refraction

The shift in direction of a wave moving from one medium to another or from a gradual change in the medium is referred to as refraction in physics. Although light refraction is the most often observed phenomena, other waves such as sound and water waves are also subject to refraction. The change in wave speed and the beginning direction of wave propagation relative to the direction of change in speed influence how much a wave is refracted. 

Refraction diagram:

In simple words, refraction is the bending of light as it passes through a transparent substance. Water, sound, and other waves are also affected. Magnifying glasses, prisms, lenses, and rainbows are all possible because of this bending, which creates light refraction. Without light refraction, our eyes would be unable to concentrate.        

Law of Refraction:

The refraction of light as it travels through various mediums follows a set of rules. The light follows the sight of refraction, and we see the refracted picture of the object, according to the two laws of refraction listed below.

• At the point of incidence, the reflected, incident, and normal all tend to lie in the same plane.

• Second, Snell’s law states that the ratio of sin of angle of incidence and refraction is constant.

                                                            sin isin r = constant

 Refraction in real life:

 Mirage in deserts and looming are examples of optical illusions caused by light refraction in our eyes.

• Because light from the bottom of the pool bends at the surfaces due to refraction, a swimming pool always appears or appears much shallower than it actually is.

• The development of a rainbow by raindrops or water drops in the air is an example of refraction because the sun’s rays bend through the raindrops or water drops in the air, resulting in the rainbow.

• Due to refraction, white light passes through the prism and splits into its component seven colours (VIBGYOR) — red, orange, yellow, green, blue, and violet.

 Refraction uses:

In optics and technology, refraction has a wide range of uses. The following are a handful of them: 

• For many purposes, including magnification, a lens exploits the refraction phenomena to generate an image of an object or body.

• The theory of refraction is used in spectacles worn by those with poor vision.

• Refraction is utilised in the safety peepholes on home doors, in cameras, inside movie projectors, and in telescopes. 

Refraction through lenses:

After travelling through air and into glass, light rays are refracted. The light rays travelling from the air to the lens are either diverged from the surface or converged from the surface of the lens by using certain types of spherical lenses, which are primarily concave or convex. Telescopes and microscopes both employ lenses. They’re also necessary for cameras and projectors. Our own eyes are an example of a spherical lens because they feature a convex lens. The image seems inverted at first, but when the optical nerves in the blind spot send the impulses to the brain, it is processed, and we see the image in its proper orientation. Important terminology for refraction through lenses include:

 The actual glass sphere, of which the provided lens is a component, has a centre of curvature.

• When two spheres are part of a lens, the principal axis is the imaginary line that connects the centres of curvatures of both spheres.

• In the case of a convex lens, the principal focus is a point on the principal axis where light rays that are parallel to the principal axis meet (or appear to meet after we do extrapolation in a concave lens).

• The optical centre is a position within or at the centre of the lens where the diameter of the lens and the primary axis intersect.

• The distance between the focus and the optical centre is known as the focal length.

Change of Speed Causes Change of Direction:

The refraction of light occurs whenever light passes through a medium with a variable refractive index or optical density. The change in speed is the reason for the change in direction.

• When light travels from air to water, it slows down and changes its angle or direction.

• The degree of bending in light refraction is primarily determined by two factors:

• The incident ray’s angle of incidence – When light penetrates a substance at a larger angle, the refraction of light increases dramatically, making it more visible to the human eye. However, if light penetrates a substance at a 90-degree angle to the surface, it will slow down rather than change direction.

• Change in Speed – When a substance causes light to speed up or slow down as it passes through it, the refraction of light increases.

Conclusion:

We can deduce that light appears to travel in straight lines by looking at the common optical phenomena that surround us. The wave theory of light became slightly inadequate for examples of light interaction with matter somewhere in the twentieth century, and light often acts like a stream or system of particles. This debate over the true nature of light raged on for years until a current quantum theory of light emerged, claiming that light is neither a smooth wave nor a ‘particle’ in nature — the new theory connects light’s particle qualities to its wave nature. The straight-line propagation of light is used to explain refraction.