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The suggested time for exploring this discussion about the topic of the propagation of light is 45 minutes.
Discussion
Discussion
Light
Light
Light, or visible light, is electromagnetic radiation visible to the human eye. Visible light is generally defined as wavelengths between 400 and 700 nanometers (nm), corresponding to frequencies between 750 and 420 terahertz, between infrared (longer wavelengths) and ultraviolet (shorter wavelengths).
In physics, "light" can more broadly refer to electromagnetic radiation of any visible wavelength. In this sense, light is gamma rays, X-rays, microwaves, and radio waves. The main characteristics of light are intensity, direction of travel, frequency or wavelength spectrum, and polarization. Its speed in a vacuum, 299792458 m/s, is one of the fundamental constants of nature. Like all types of electromagnetic radiation, visible light is propagated by massless elementary particles called photons, which represent quanta of the electromagnetic field and can be analyzed as waves and particles. The study of light and optics is an essential field of research in modern physics.
The main source of natural light on Earth is the sun. Historically, another important source of light for humans has been fire, from ancient bonfires to modern kerosene lamps. With the development of electric lights and electrical systems, electric lighting effectively replaced incandescent lighting.
Theory about light
Theory about light
Rene Descartes
Rene Descartes
The first person to investigate and define the idea of refraction was Rene Descartes. To create a rainbow, he combined water and sunlight in a sphere-shaped glass. He explained how rainbows are created by refraction. Then, using a prism, he watched the colors of light that formed.
He also used the idea of the universe, a material that permeated the universe but was invisible, to explain how the different colors of light first appeared. He imagined the box to be formed of little balls whirling in unison. This conference shed some light. The spheres' rotational speed altered as the interface approached the edge of the prism, producing colors.
Sir Isaac Newton
Sir Isaac Newton
Sir Isaac Newton also investigated how a prism produces different hues of light. He came to the conclusion that the variations in refraction were caused by the different masses of the various colors of light.
The same force is produced by matter and light particles. Light colors bend differently depending on their bulk and inertia.
Large mass and inertia light particles bend less when passing through the interface of matter than when the same force of matter is acting on them.
Dual Properties of Light
Dual Properties of Light
Now we see that light can also be modeled as particles - massless photons with particular energy and momentum. We call this dual nature particle-wave duality, meaning that EM radiation has both particle and wave properties.
Particle Theory of Light
Particle Theory of Light
The particle theory of light was proposed by Newton in 1704 in his treatise Optics. This is the simplest theory of light, where light is supposed to be composed of microscopic particles called "bodies", and therefore this particle theory of light is also called the corpuscular theory of light.
The most famous proponent of the particle theory of light was Isaac Newton. Studying the properties of light in the 1660s, Newton discovered that white light is composed of several colors.
Wave Theory of Light
Wave Theory of Light
In 1678, Huygens proposed that every point exposed to light interference becomes a source of a spherical wave. The sum of the secondary waves created as a result of the disturbance determines what form the new wave will take. This theory of light is known as the "principle of Huygens".
Using the above principle, Huygens successfully derives the laws of light reflection and refraction. He also managed to explain the linear and spherical propagation of light using this theory. However, he was unable to explain the diffraction effects of light. Later, in 1803, Thomas Young's experiment on the interference of light proved Huygens' wave theory of light correct.
Reflection and Refraction of Light according to particle and wave theory
Reflection and Refraction of Light according to particle and wave theory
Two complementary theories have been proposed to explain the behavior of light and the form of its movement.
1. Particle Theory: Light consists of a stream of small particles because it travels in straight lines at great speeds and is reflected from mirrors in a predictable way.
2. Wave Theory: Light is a wave because it undergoes diffraction and interference (Young's double–slit experiment).
The scientific study of the behavior of light covers reflection, refraction, polarization, diffraction of light as it passes by the edge of an opaque object, and interference patterns resulting from diffraction.
Reflection
Refraction
Polarization
Diffraction
Propagation of Light
Propagation of Light
Light consists of two waves oscillating perpendicular to one another. One of the waves is a magnetic field while the other one is an electric field. It propagates through space at a speed of 299,792,458 meters per second (3.0 x 10^8 m/s).
The electromagnetic (EM) spectrum is composed of light waves with different wavelengths and frequencies. The wave components of the EM carry varying amounts of energy.
White light, the visible part of the electromagnetic spectrum consists of colors, namely red, orange, yellow, green, blue, indigo, and violet. This has an acronym ROY-G-BIV. When it passes through a prism, they are dispersed or split into its component colors with different wavelengths.
When light is incident on surfaces, it can be reflected, absorbed, or transmitted.
When the colors of light incident on a surface are reflected the object appears white.
Light waves are incident on a leaf. All the colors of white light (ROY-G-BIV except green) are absorbed by the surface. As such, green is reflected to our eyes. This is the reason why this leaf appears green.
Light rays that fall on opaque objects are absorbed by the substances and appear black.
Light rays that fall on smooth surfaces bounce off or reflect with equal angles of incidence and reflection.
The colors of light incident on a transparent material will pass through the object completely.
Sunlight bumps into a mixture of particles in the atmosphere. The scattering of the component wavelengths depends on the size of the particles. This gives rise to the colors that we see in the sky.
For more understanding let's watch this!
For more understanding let's watch this!
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