What happens when lighting occurs

The light as a symbol for the contrast to the darkness is mostly in connection with an enlightenment or a new knowledge. The symbolism of the color yellow has to do with light. Often light is used as a symbol for non-material things like spirit or happiness in lifek used. The representation of light as a physical phenomenon shows how difficult it is to grasp light scientifically and conceptually.
  
If you heat a piece of metal, it starts to glow after a while. During this process, thermal energy is converted into light. The hotter the piece of metal, the higher the light output. At 700 ° C it glows dark red, at 1200 ° C it glows bright orange and above 1300 ° C it begins to glow. If heat energy is supplied to metal atoms, the atoms are put into an excited state, whereby they emit light. Light is created by burning chemical energy (flame), by converting electrical energy (incandescent lamp) or by converting atomic nuclei (stars). In the sun, the nuclei of hydrogen atoms fuse to form helium nuclei. Huge amounts of energy are generated that radiate into space as heat or light. The surface temperature of the sun is more than 6000 ° C. Heat radiation of around 175 billion megawatts hits the globe alone.
    
As early as 1690, the Dutch physicist Christiaan Huygens assigned a wave nature to light - based on sound waves. In the 19th century, the theories of physicist James Clerk Maxwell supported the assumption that light travels as an electromagnetic wave. Most electromagnetic waves such as radio waves or X-rays are not visible to our eyes. The waves differ in their wavelength: radio waves can be several hundred meters long, while cosmic radiation has wavelengths in the almost unimaginable range of millionths of a nanometer (1 nm = 1 billionth of a meter). The wavelength of the light that is visible to us is between 765 nm and 385 nm and is known as the optical spectrum. The optical spectrum itself is made up of various electromagnetic waves that produce different color perceptions in our eyes.
  
 
Optical spectrum of light


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Visible light only makes up a small part of the entire spectrum.
 
   
The London doctor Thomas Young recognized in 1817 that light waves do not move as longitudinal vibrations like sound waves, but transversely. Transverse waves oscillate perpendicular to the direction of propagation.
    
 
Comparison of light waves and sound waves


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Transverse waves oscillate vertically, longitudinal waves parallel to the direction of propagation.
 
   
The eye has color sensory cells, the cones, on the retina, each of which is sensitive to a certain wavelength of light. If they are excited at the same time, the color impression obtained is white. Sunlight can be described as a mixture of several electromagnetic waves from the optical spectrum. The additive color mixing provides experimental proof: white is created by mixing several colored light sources.
  
    
Albert Einstein pointed out that light can also take on other forms. In 1905 he claimed that light, in addition to its wave nature, must also have the character of a particle, since it can knock electrons out of the plate when it hits a metal plate. He called the "light particles" photons. The effect described is known as the photoelectric effect and is the technical basis for photovoltaic electricity generation from sunlight.
   
The property of light to behave like a wave as well as a particle is one of the strangest phenomena in nature. Niels Bohr coined the term complementarity for this “as well as” phenomenon. The arrangement of the structure for the experiments is crucial in order to discover properties through the light. An experimental setup proves the wave nature of light, another setup proves its particle nature. Since this discovery, it has been assumed that the objects of nature are not clearly defined, but that man himself can decide to a certain extent what nature is like. Some philosophers go much further and claim that nature (and everything that lives and arises in it) is a pure thought structure of the human being. It would only begin to exist when man conceived it. This philosophical direction is called constructivism.