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Light and Color. Write down the text in RED at least. . What is Light?. Light is a type of energy that travels as a wave Light is an Electromagentic Wave It has both an electric field that travels up and down, and a magnetic field that travels back and forth
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Light and Color Write down the text in RED at least.
What is Light? • Light is a type of energy that travels as a wave • Light is an Electromagentic Wave • It has both an electric field that travels up and down, and a magnetic field that travels back and forth • Light is a transverse wave (different from sound)
What is light? • Light can travel through empty space because it doesn’t need particles to crash together. • It can travel through air, glass, some plastics, and some liquids.
What is light? • The speed of light is unbelievably fast – about 300,000,000 meters per second! • Light is about 880,000 times faster than sound. That is why you see lightning much faster than you hear thunder.
How is light Produced? • Incandescent light is produced by heat. • The filament inside a bulb is made of a metal called tungsten. When tungsten gets hot, it changes the heat into light waves. • Electricity flows through the filament to make it hot
How is light produced? • Fluorescent light is produced when electrons of the gas atoms inside the bulb are energized and jump to the next valence level. • Not much heat is generated, so fluorescent bulbs use less electricity
How is light produced? • LED stands for light emitting diode. • LED light is produced when electrons move through a semiconductor diode, the e- drop to lower valence shells, and send out packets of light, or photons, when they drop.
How is light produced? • Light from the sun is produced by gamma rays exploding from fusion reactions inside the core of the sun. • All wavelengths of light in the EM spectrum are produced by the sun, but humans sense just light and heat.
Light carries energy. • Biological energy comes from plants using solar energy to conduct photosynthesis • The energy to create weather comes from solar energy • Light can be converted to electrical energy directly
Light carries information • Light travels through tiny glass tubes, bouncing off the walls of the tube on the inside. • These bursts of light can carry information in the form of on-off signals
Light travels in a straight line • Light moves away from a source in all directions at once – like a ripple in water. • The intensity of light decreases as it moves away from the source.
Visible light is made of colors • The visible light from the sun is actually all of the wavelengths of light coming at once. • A prism (or water drops in the air) can split the white light into its colors
Sensing Light • Humans can only detect visible light and infrared light (as heat.) • Many insects, such as bees, can detect UV light
Sensing Light • The Hubble Telescope has instruments which can detect all wavelengths of the EM spectrum. The Orion constellation viewed in various wavelengths of the EM spectrum