We know light as electromagnetic radiation, which can be either visible or invisible. It is emitted by any object that emits energy in the form of waves, like a light bulb, lamp, or laser. The photons of light have both particle and wave properties. They are particles when they travel at the speed of light (186,000 miles per second) and waves when they move slower than that. Here we are going to cover all the topics related to light one by one.
What is light? And its characteristics?
- The word light is used to describe a form of electromagnetic radiation. It travels in waves and has a frequency measured in Hertz (or cycles per second).
Light waves are made up of tiny particles called photons, which have no mass but are very small. Photons can travel at the speed of light” 186,000 miles per second ( or 3 x 10^8 meters per second)! This means that when one photon hits your eye, it will hit you before another can hit your eye on its way back to where it came from (and vice versa).
Wave theory of Light
Particles theory of Light
Quantum theory of light
How is light produced?
- Light is produced by electromagnetic radiation. Electromagnetic radiation is any form of energy (energy that can transfer to other matter) that travels through space in the form of waves. The most common types of electromagnetic radiation are visible light and infrared (IR).
Light has many properties, including wavelength and frequency. A wavelength is how far apart the peaks and troughs on an oscillating waveform are spaced; a higher frequency means there are more peaks per second than troughs per second. The speed at which an object moves through space determines its frequency: if you travel faster than c (the speed of light), then your wavelength will be shorter (less distance between peaks). If your body moves slower than c, then its wavelength will be longer (more distance between troughs). Light electromagnetic radiation we see and experience is called visible light.
The range of wavelengths in which visible light can be observed is from about 400 to 700 nanometers (nm).But what about light that does not falls in this category?
The ultraviolet spectrum can be subdivided into three bands
- The first band (1st) is known as ultraviolet-A or UV-A for short. This part of the spectrum contains high levels of the ionizing radiation corresponding to ionization levels between 5 eV and about ten keV. This kind of radiation has been used for sterilization because it has little penetration depth through air layers due to its short wavelength, allowing only photons with sufficient energy per photon (E/ph).
Therefore no molecules could absorb this type, especially if they were closer than 1Â mm away from the skin surface, thus protecting yourself against germs or bacteria residing on your hands, etc., also reducing the risk caused by harmful chemicals such as pesticides during gardening activities like lawn mowing, etc.
- V ~ violet
- I ~ indigo
- B ~ blue
- G ~ green
- Y ~ yellow
- O ~ orange
- R ~ red
The wave theory of light was first proposed by Thomas Young in 1804. A wave model describes light propagation as an oscillating disturbance, like sound or water waves.
Young’s theory was later modified by James Clerk Maxwell and Albert Einstein, which explains how electromagnetic radiation interacts with matter (e.g., electrons) and can induce them to move in specific ways due to its interaction with photons, elementary particles making up electromagnetic waves themselves.
The wave theory of light states that there are two types of waves: Light can be described as either a longitudinal or transverse wave depending on whether you’re looking at it from its source (the sun) or destination (your eyes). Longitudinal and transverse. Longitudinal waves move along the direction they’re traveling, while transverse waves move at right angles to their movement.
The particle theory of light is a theory that states that light is made up of particles called photons.
The particle theory of light says that the light travels in a straight path in the form of small energy packets, called ‘quanta,’ and in terms of sunlight, these quanta are called ‘photons.’
Quantum theory of light is a branch of physics that deals with the behavior and interaction of light and other types of electromagnetic radiation.
You can say the quantum theory of light is a mixture of the wave theory of light and particle theory of light because this theory states that ‘light is a make-up of small energy packets called photons and also have wave effects.
It was developed in the early 20th century by Albert Einstein, Max Planck, and Erwin Schrodinger. It grew out of earlier work on related topics such as thermodynamics, special relativity, classical electromagnetism (including Maxwell’s equations), quantum mechanics, statistical mechanics/quantum field theory, and photoelectron-dynamics (physics). In this sense, it was primarily concerned with how things behave at microscopic scales -- visible effects like those observed from everyday objects like mirrors or lenses become less significant when you consider quantum physics alone.
Cosmic rays are a energy in the form of high radiation that originate from outside our solar system. On reaching Earth, these rays collide with particles of our upper atmosphere to produce a “shower” of particles.
Gamma rays are electromagnetic radiation with the highest frequency and the most penetrating power. They have the shortest wavelength of all types of light. Gamma rays can be produced by any object with a temperature above about 10 million degrees Celsius (18 million degrees Fahrenheit).
For example, a supernova explosion can produce gamma rays in response to its violent collapse into itself; in fact, this process is what gives us our understanding of how stars die! The cores of active galaxies also give off gamma rays because they’re hot enough for their atoms to emit them at higher than average temperatures,” but these are not necessarily related to nuclear fusion processes inside stars or other celestial bodies like planets; instead, these emissions come from electrons moving near atomic nuclei at very high speeds (about 100 million meters per second), which produces an enormous amount of energy when they collide head-on with an electron attached to another atomic nucleus” a process called pair annihilation.
X-rays are a form of electromagnetic radiation. They have a shorter wavelength than visible light but longer than microwaves and infrared radiation. The electrons in the atom emit x-rays when they move extremely fast. X-rays can harm humans, so they are used in medicine only under controlled conditions like in hospitals or nuclear power plants where there is no risk of exposure.
Ultraviolet light is the electromagnetic radiation of a wavelength shorter than visible light but longer than X-rays, 10 nm to 400 nm, and energies from 3 eV to 124 eV.
In the electromagnetic spectrum, only the light on the part of the visible spectrum can be seen from an average human eye. These are generally pronounced as VIBGYOR and stand for
The range of wavelengths in which visible light can be observed is from about 400 to 700 nanometers (nm).
Infrared light is the next higher frequency of light from red. It's just below visible light and can be seen with a device called an infrared camera. Infrared cameras are used in remote control devices, night vision goggles, and other applications where you need to see objects that aren't quite as bright as they should be.
Here we observed how light shows different nature; we understand wave theory, particle theory & quantum theory of light with all the spectrums, e.g., cosmic rays, x-rays, gamma rays, visible spectrum, ultra violate rays and infrared rays, and I hope now you are familiar to light and the characteristics of light.Continue with Characteristics of light - 2