Light
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Like infrared radiation, light is a form of energy called electromagnetic radiation. It travels as a wave, called an electromagnetic wave. Like a sound wave, an electromagnetic wave has a specific frequency and wavelength. Infrared radiation and light from the Sun travel through the vacuum of empty space to reach Earth. When light hits a surface, it may be:
- Transmitted through it
- Reflected off it
- Absorbed into it
- Transmitted through it
- Reflected off it
- Absorbed into it
![Picture](/uploads/2/2/1/1/22119214/7269308.jpg)
The electromagnetic spectrum describes the various types of electromagnetic radiation based on their wavelengths. Radio, representing wavelengths from a few feet to well over a mile, is at one end of
the spectrum. Gamma ray radiation is at the other end: the wavelength of the harder types is so short, in the subatomic range, that we do not have instruments capable of directly measuring it.
These are the types of electromagnetic radiation:
- Gamma rays
- X-rays
- Ultraviolet rays
- Infra-red radiation
- Microwaves
the spectrum. Gamma ray radiation is at the other end: the wavelength of the harder types is so short, in the subatomic range, that we do not have instruments capable of directly measuring it.
These are the types of electromagnetic radiation:
- Gamma rays
- X-rays
- Ultraviolet rays
- Infra-red radiation
- Microwaves
![Picture](/uploads/2/2/1/1/22119214/15280.jpg)
Reflection is the returning, or "bouncing" of a wave off of a surface which resists that kind of wave. When it reflects, it always does so at the exact same angle it came in at. If you shine a light directly at a 90 degree angle, it will come directly back at a 90 degree angle. If you shine it 45 degrees to the left, it will exit 45 degrees to the right. The angle at which the light comes in is called the angle of incidence, while the angle at which it exits is called the angle of reflection. This observation is called the scientific law of reflection, which states that the angle of incidence is equal to the angle of reflection.
The image to the left is an example of reflection.
The image to the left is an example of reflection.
Refraction is the change in direction of a wave when it passes into a new substance. The reason the light changes direction or "bends" is because each different substance has it's own effect on the speed of light within itself. Every substance has an optical density, this number, called the substance's index of refraction, is how well light passes through it, the higher the density, the harder time light has moving through it.
The image to the right is an example of refraction of light.
The image to the right is an example of refraction of light.
![Picture](/uploads/2/2/1/1/22119214/7412334.jpg?291)
There are three major sources of light. Objects that give off their own light are said to be luminous. For example: A torch or Fluoro light.
Light sources can be incandescent. They emit light because they are hot. For example: The Sun, stars and flame.
Living things that emit light without heat are referred to as bioluminescent. For example: A glow worm or an angler fish (like the one off 'Finding Nemo' which has a light on its head).
Light sources can be incandescent. They emit light because they are hot. For example: The Sun, stars and flame.
Living things that emit light without heat are referred to as bioluminescent. For example: A glow worm or an angler fish (like the one off 'Finding Nemo' which has a light on its head).
![Picture](/uploads/2/2/1/1/22119214/4850888.jpg?339)
The colour of anything depends on the type of light sent to our eyes. Light is necessary if we are to have any perception of colour at all. An object is coloured because of the light it reflects, all other colours are absorbed into that specific object. For example: light sends the colours of the rainbow. When this light is sent to an apple it absorbs every colour except red (it reflects off the apple). So therefore the apple is red. Refer to the diagram above for more understanding.
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