Refraction of Light - Definition, Examples, FAQs
Refraction of light is an important phenomenon in optics that explains how light changes its direction when it passes from one medium to another, such as from air to water or glass. This bending of light occurs due to a change in the speed of light in different media. Because of refraction, many everyday effects can be observed, like a pencil appearing bent in water, the bottom of a pond looking raised, and the working of lenses in spectacles and cameras. Refraction of light plays a vital role in understanding optical instruments and vision. In physics, it helps students learn about refractive index, laws of refraction, and light behaviour in transparent materials. This concept is widely used in science, engineering, and real-life applications.
This Story also Contains
- What is Refraction?
- What is Refraction of Light?
- Causes of Refraction
- State the Laws of Refraction of Light
- What Is the Refractive Index?
- Examples of Refraction of Light
What is Refraction?
The change in direction of a wave traveling from one medium to another caused by its change in speed is known as refraction in Physics. In deep water, for example, waves travel faster than in shallow water. Sound waves travel faster inside of the warm air than in cold air.
What is Refraction of Light?
Refraction of light is the phenomenon in which the path of light changes when it passes from one medium to another due to a change in its speed.
When light travels between media of different optical densities, its speed changes, causing the light ray to bend at the boundary. Refraction explains effects such as a pencil appearing bent in water and the apparent depth of a pond.
Causes of Refraction
Refraction of light occurs due to a change in the speed of light when it passes from one medium to another.
The main causes of refraction are:
Change in medium: When light travels from one medium to another (like air to water), its speed changes.
Change in optical density: Different media have different optical densities, which affect the speed of light.
Change in wavelength: The wavelength of light changes in different media, causing bending of light.
Because of these changes, the direction of light alters at the boundary of two media, resulting in refraction.
Also read -
State the Laws of Refraction of Light
Refraction follows two basic laws:
The laws of refraction of light are:
1. The incident ray, the refracted ray, and the normal at the point of incidence all lie in the same plane.
2. For a given pair of media, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.
$
\frac{\sin i}{\sin r}=\text { constant }
$
This constant is called the refractive index of the second medium with respect to the first.
Snell's Law
Snell's Law provides the mathematical relationship between the angles of incidence and refraction when light passes from one medium to another.
$
\frac{\sin \left(i\right)}{\sin \left(r\right)}=\frac{n_2}{n_1}
$
Where:
- i is the angle of incidence (the angle between the incident ray and the normal)
- r is the angle of refraction (the angle between the refracted ray and the normal)
- $n_1$ is the refractive index of the first medium (where the light is coming from)
- $n_2$ is the refractive index of the second medium (where the light is entering)
What Is the Refractive Index?
Refractive index is a measure of how much light slows down when it travels through a medium compared to its speed in vacuum.
It is defined as the ratio of the speed of light in vacuum to the speed of light in the given medium.
$
n=\frac{c}{v}
$
where
- $n=$ refractive index of the medium
- $c=$ speed of light in vacuum
- $v=$ speed of light in the medium
Examples of Refraction of Light
- A pencil or stick appears bent when partially immersed in water.
- The bottom of a pond appears raised when viewed from above.
- A coin placed in a bowl becomes visible when water is poured into it.
- Twinkling of stars due to refraction of light in Earth’s atmosphere.
- Mirage formation on hot roads or deserts.
- Spectacles and lenses work on the principle of refraction.
Frequently Asked Questions (FAQs)
It's tough to photograph a fish swimming in water due to light refraction.
The reason for this is that the light beams that travel from the fish to the shooter curve at the water-air boundary. As a result, the shooter only sees a picture of the fish, not the actual creature
On a hot summer day, the air directly above the road surface is extremely hot, whereas the air at higher elevations is cool.
The refractive index of air increases with density, as we all know.
As a result, the colder air towards the top has a higher refractive index than the hotter air near the road.
The hotter, thinner air goes faster than the cooler, denser air above it.
The temperature drops with height on hot days.
As a result, the refractive index of air rises with altitude.
An optical fibre is a very thin glass or plastic fibre with a radius of around a micrometre (10-6 m).
A light pipe is formed by a group of such tiny fibres.
When a light ray is incident perpendicular to a surface's interface, it does not deviate.
When a light beam strikes a surface at a greater than critical angle, it does not refract but instead reflects back into the original medium.
The temperature of the surrounding air changes as a result of the campfire's heat convection.
This causes a constant change in the density and refractive index of air.
The refractive index of air changes with time, changing the refracted path of light ray
