Photons are particles of energy that are sent or received by the eye from an external source. Light Energy has many different forms, but generally, we think of light in its yellow state as being made of bits of light atoms (ions) in a very high energy environment. These atoms move in a very narrow range of frequencies when they are in the sunlight. The energy emitted by them is called electromagnetic radiation. The visible light of sunlight, though very powerful, is only one form of electromagnetic radiation produced by the sun.
Photons, like electrons, are in a state of mutual motion. When a molecule is made of hydrogen atoms, for example, a proton will bump into a hydrogen atom to produce energy (and heat). The same thing happens when the hydrogen bonding with another carbon atom produces an electron (and gives off energy). In this way, the sun gives off electromagnetic radiation in the form of visible light. Light is one of the most important types of radiation and the main source of our communication system. Without the sun, we would all be blind.
The sun gives off electromagnetic radiation in the visible light spectrum but not in the ultraviolet or x-rays. For this reason, we can see under the black sky but cannot see the infrared radiation emitted by sulfur dioxide or microbes beneath the ice. This is where photovoltaic or solar energy comes in. Solar power is used for heating water, generating electricity for homes, cooling air conditioning, running lights and motor vehicles, and so much more.
A major class of the theory of light energy deals with the Photosynthetic Organic Reaction (POR) in which sunlight is converted into energy and used by living things to grow and reproduce. Photosynthetic organisms are bacteria, algae, and other forms of life. They use light energy in the form of adenosine triphosphate (ATP), in order to create energy for their own cellular processes. If the reaction is interrupted, however, the bacteria and other photosynthetic organisms die. This is how plants make food, and the process is why some photosynthesis only occurs in dark environments: it is necessary for photosynthesis to occur in dimly-lit conditions.
Photons of light energy will pass through the semiconductor material on the inside of a CCD, which is also called a photocell. A photodiode is any type of semiconductor material that absorbs photons when they are struck there. The most common of these is the silicon material found in most of the modern digital cameras. The silicon atoms have their positive charge removed by an electric current passing through, creating a tunneling effect that causes them to “bounce” or return the photons. This allows the electrical current to pass through the silicon, which gives the excited state that is the key to turning light energy into electricity.
Photosynthesis occurs in nature when sunlight or other forms of natural energy are used to break down food using photosynthesis. Organic compounds such as carbon dioxide, water, and oxygen are the building blocks of life, and together they are necessary for the process to occur. The sun is one of the most effective sources of this energy, but it is relatively inefficient for converting it directly into oxygen and other nutrients. Instead, plants and other photosynthetic organisms rely on chlorophyll to absorb sunlight and use it to produce food. When enough of the chlorophyll on the leaf surfaces is exposed to light energy, the molecules will absorb the energy and become energized.
Oxygen is similar to light in that it can be absorbed by organic compounds and used to produce energy. However, oxygen is much more reactive than light, being rather destructive in causing changes in a chemical reaction. This is why you cannot burn coal or wood because the flames would be too intense for oxygen to interact with the carbon dioxide in the atmosphere and release its energy without change. If you were to attempt to produce electricity with coal, your efforts would fail miserably, and there would be an environmental impact that was not intended. This is why many nations have banned the production of electricity using this fossil fuel.
Photosynthetic energy conversion processes are useful in thermodynamics because they provide the basis for a wide variety of chemical reactions and biological functions. These include the photosynthetic reaction that transforms sunlight into usable energy and the photosynthetic enzyme that convert food into starch. Many forms of life on Earth use such energy conversion processes to sustain their existence. In fact, some bacteria alone require so much of this energy to grow that they have been known to outnumber human beings on the planet.