Everything which we see happening around us is because of light. A particular frequency of electromagnetic radiation (which is also being referred to as light), which is around 390 to 700 NM, is visible to the eyes of the human. Even if we look at any particular leaf, we already know that it is green in colour because there is a light that bounces off the leaf to our eyes and tells us that it is green in colour. Light is any form of energy, just like all other energies, which is produced from a source. These sources are called light sources.
Types of Light Sources
In reality, we have a lot of sources of light, but all of them can be categorised under two categories which are known as natural sources and artificial sources.
Natural Light Sources
In our universe, there are a lot of objects that emit light of their own. Some of the lights from these sources can reach the surface of the earth. The things which are present in nature and have the ability of emitting lights are given below.
The Sun is one of the major sources of light for our planet Earth. The Sun is considered as a massive ball of fire that produces massive energy by the nuclear fusion at its centre. This energy from the Sun comes out in the form of light and heat. The major factor which is behind the sustainability of life on the planet Earth is the light from the Sun.
Every star also produces light, but because of the huge distance between the Earth and these stars, only a small amount or sometimes no amount of it reaches the surface of the earth.
The moon also provides light, but it doesn't produce light of its own. The light which we get from the moon is the light that is being reflected by the moon from the Sun.
Certain natural phenomenons also emit light, such as volcanic eruptions and lightning.
There are some living organisms also who can produce light of their own. They are called bioluminescence. Some examples of these are jellyfish, fireflies, glow worms, etc.
Artificial Light Sources
Light can also be produced artificially apart from natural sources. The different lights which can be produced artificially come under three categories. Those categories include incandescent sources, luminescent sources and gas discharge sources.
Under incandescent sources, certain objects are being heated to a high temperature till they begin to emit light. In this process, both infrared and visible lights are being produced. Examples of incandescent sources are incandescent lamps and candles. An incandescent light source is the most common type of source in which Sun, light bulbs and fires can be included. Incandescent light is a type of light source which includes the vibration in the entire atom, as when the atoms are heated, then the thermal vibrations in the form of electromagnetic radiations are released. Depending on the temperature, the materials vary in emitting energy; at a low temperature of the materials, the emission of radiation takes place through infrared wavelengths in the photons. A common example of the incandescent light source is when a metal is heated, the atoms present in the metals gets vibrated and emit photons which emit radiation to make it visible to the human eye by raising the wavelength in the spectrum.
Fire is the most common example of incandescent light, as fire includes a chemical reaction that releases both gases and heat, causing the material to reach a high temperature, causing the material and gases to be incandescent (lighten up).
Similarly, light bulbs produce heat through which electrical current passes, raising the temperature of the cable and finally providing incandescent to the cable.
Under luminescent sources, lights are being produced by accelerating changes in the material of luminescence. The common way of doing this is bypassing the current through the material. Its examples are electric bulbs and fluorescent tube lights. As compared to incandescent light sources, these types of sources involve only electrons instead of the whole material vibrations, which takes place in normal or lower temperatures making it different from the Incandescent type of sources. Basically, we can say that when the electrons emit some part of their energy in the form of electromagnetic radiation, then the type of light is known as luminescence light. When an electron drops down in temperature, then the specific light colour is produced through the energy level decrement. Some common examples of Luminescence light sources are neon lights, fluorescent light, bioluminescence, fluorescence light, etc. Fluorescence light is the most common example of luminescence light source, which can be further divided into two parts which are electro-luminescence and photo-luminescence, which can include computers, screens and televisions. Bioluminescence is also the most common example of luminescence which even includes animals like fireflies.
Under gas discharge sources, the electricity is being passed through a certain gas at very low pressure for producing light. Its examples include sodium lamps and neon lamps.
More About the Topic
There would be no world if lights were not there, as light provides us with the ability to see things. Plants also need light which is provided by the Sun in the form of sunlight through which many processes in nature take place, so we can say that the main source of light on earth is sunlight. Light comes from different sources, which are known as light sources, and these light sources can be defined as the sources through which light (a form of energy) is produced. Light is an energy source that can travel as a wavelength and can travel very quickly. Rainbow formed in the air is the very common example of light striking the droplets of water to separate colours with different wavelengths, making our eyes see those different wavelength colours forming the rainbow. We can say that light is a form of electromagnetic radiation whose particular particle can produce radiation of around 390 – 700 nm, which is visible to a human eye. The human eye can see almost all types of light except for infrared and ultraviolet rays. Our brain further processes the light captured by our eyes, translating the energy bandwidth into the colour spectrum our brain and eyes are sensitive to. The artificial life created by humans is formed by the movement of molecules (rational as well as vibrational) having the transitions with molecules or atoms. An atom or molecule gets excited and enters a state which is considered absorbing, while it can be said as entering an emitting state when these atoms or molecules relax. If the light is in any other form of electrical energy, then these electrical energies can be easily converted into light energy.
Basically, we can say that by exciting energy with any means necessary at that particular region, then it is said to be light, as the light lies in the visible spectrum in the form of energy or wave. In the modern world, humans are also creating artificial light, which is the most suitable form of electrical energy in the current world. Neon lights, light bulbs and fluorescent tubes are very good examples of electrical light. Lasers are also a good example of artificial light.
Difference Between Natural Light and Artificial Light
The most important difference between natural light and artificial light is that natural light can be found in nature, but artificial light is electronic, which is formed with the help of advanced technology. Natural light has no control over the usage as it is based on the duration of time, but this is not in the case of artificial light. Usage of artificial light is limited. The amount of light produced is the main factor of using artificial light. If the artificial light is produced in less quantity, then the consumption is also low.