For human beings, light is first and foremost a wonderful phenomenon that illuminates the world, and it makes everything appear in our eyes. Without the light, what will happen to us? Ever since humanity opened its eyes and observed the world, the sun has been revered as the god of light, the source of life and safety. Then the emergence of rational questioning makes us think about the nature of the phenomenon of light. So, what is light?
Light is a form of energy produced by matter. In order to understand how it is produced, we must first study the constituent part of matter, namely atoms.
The atom is a bit like a honeycomb, surrounded by large swarms of bees: the hive corresponds to the nucleus, while the large swarm of bees represents the cloud of electrons around the nucleus.
However, the nucleus and electrons have a special property: they are both charged. What's more, the charges they carry are reversed. We refer to the charge carried by the nucleus as the "positive" charge, while the electron carries the opposite charge, the "negative" charge. In the world of atomic particles, opposites attract each other; therefore, nuclei and electrons attract and bind each other within atoms.
In addition, there is an important difference between bees and electrons: bees can fly freely around the hive, but electrons cannot; although there is an interaction between the nucleus and the electron, the electrons can only fly in a "orbit" (what scientists call an "orbit") at a specific distance.
While electrons can't choose their place around the nucleus at will, they can adjust their distance from the nucleus by changing their orbitals. To do this, the electron needs to change its energy to match the orbital energy it is going to be.
For example, if electrons are to travel from an orbit away from the nucleus to an orbit closer to the nucleus, they need to release some of their energy. The energy released has a charged component and, like all negatively charged substances, this part of the energy is magnetic. Electrons are in the form of small "energy packets" called photons, rid of their excess energy.
Photons are energy particles that have no mass and move extremely fast. Curiously, the moving photons interact with matter in the same form as waves, that is, like waves on the surface of the water. And because this wave is both charged and magnetic, we call it "electromagnetic waves".
It can be seen from this that photons and electromagnetic waves are synonymous in some sense. In everyday parlance, they share a common name: light. But in fact, a photon is actually a "light particle", and electromagnetic waves are "light waves".
Light is best known as a physical phenomenon capable of producing visual sensations. Physics studies have proved that light is an electromagnetic wave, which has a wavelength of about 550 nanometers in a vacuum, floating up and down by about one-third. Through environmental adaptation effects, these inaccuracies vary with species and correspond to the regions of the electromagnetic spectrum with the highest solar irradiance on the Earth's surface.
The discipline that studies light is called optics. Since the propagation law of light is roughly the same as that of other electromagnetic radiation, not to mention that their wavelengths are close to the visible spectrum, the scope of optical research often extends to other electromagnetic waves in the infrared and ultraviolet ranges. That's why when we talk about black light, ultraviolet and infrared, we sometimes use the term visible light to avoid ambiguity. Light, including those invisible radiation, carries most of the Sun's energy to earth's surface and regenerates oxygen through chlorophyll photosynthesis of plants to maintain the balance of the natural environment.
For humans, light is not only essential for vision, but also an important part of happiness and social life. Illumination is both art and industry, and it is necessary to comply with legal standards; physiological optics is more concerned with human perception of light; spectroscopy links the physical measurement of electromagnetic radiation with human vision; colorimetry is related to the perception of color.
Light has a very strong symbolic meaning: it allows us to perceive objects before they touch them, and in all human civilizations it is considered to be closely related to knowledge.
BY: astro-canada
FY: Shaw
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