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Published bySybil Lewis Modified over 6 years ago
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Photons and Energy A photon is a bundle of energy.
This energy is a type of electromagnetic, or EM wave. The EM spectrum shows how the energies are related to the type of wave produced.
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The Electromagnetic Spectrum
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As you can see, visible light is only a very small fraction of the types of EM waves that are produced by the sun.
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Range of EM waves emitted by the sun
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As you can tell, the sun emits all types of radiation, but most of it is in the visible spectrum range (light). Thankfully our atmosphere absorbs most of the damaging x-rays and gamma rays from the sun. Ozone absorbs more than 90% of the UV radiation as well
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These are all EM waves and all travel at the same speed, 300,000 km/s (=speed of light)
They are a form of light we cannot see. That’s why astronomers have radio, UV, microwave and infrared telescopes. They also have gamma and x-ray telescopes but the atmosphere blocks out most of those rays.
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Energy Is Transferred 3 Ways
Conduction Convection Radiation
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1. Conduction Conduction - the transfer of energy by direct contact.
- objects toughing other things - molecular motion ex: touching a hot pot, hot water touching your skin.
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2. Convection Convection - the transfer of energy by moving masses of material - the hot water in a pot moving around - warm air coming out of the ducts - a warm breeze that blows across the ground
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3. Radiation Radiation – The transfer of energy by waves.
The waves are called Electromagnetic waves = (EM) These waves don’t need a material to travel through (a medium)
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Radiation isn’t always harmful
Normal everyday radiation includes thermal (heat), solar radiation (light from the sun), radio waves, microwaves, etc
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