Electromagnetic radiation simply a stream of photons (a bundle of energy) What are photons???
no mass travel in a wave like pattern move at the speed of light contain a certain amount (or bundle) of energy all electromagnetic radiation consists of photons
When electrons jump from outer shell (higher energy level) to inner shell (lower energy level), closer to the nucleus, they give up energy This energy is released in the form of a photon The further the electrons jump, the more energy the more energy the photons have As the sun loses energy, this energy is released in the form of photons
Mass-less photons that travel in a wave-like pattern at the speed of light Each photon contains a certain amount of energy. The different types of radiation are defined by the amount of energy found in the photons.
Which side of the spectrum do you think has more energy?
The different types of radiation in the Electromagnetic spectrum, in order from lowest energy to highest: Radio Microwaves Infrared Visible Ultraviolet X-ray Gamma Ray
- Your radio captures radio waves emitted by radio stations, bringing your favorite tunes Stars and gases emit radio waves
Microwave radiation will cook your popcorn in just a few minutes used by astronomers to learn about the structure of nearby galaxies, and our own Milky Way!
Night vision goggles can pick if Infrared radiation emitted from our skin as well as heat Helps astronomers map the dust between stars.
- Only part of the spectrum that our eyes can see - Visible light is separated to tell astronomers what stars are composed of
emitted by the Sun and are the reason skin tans and burns "Hot" objects in space emit UV radiation
Doctors use to look at bones and teeth Emitted by hot gases in universe
Emitted by radioactive materials The biggest gamma-ray generator of all is the Universe.
Radio waves, visible light, X-rays, and all the other parts of the electromagnetic spectrum are fundamentally the same thing. They are all electromagnetic radiation, they are all photons traveling at the speed of light.
Only difference is the energy in the photons. Radio waves - low energy Gamma Rays high energy
Wavelength the distance from the top of one wave to the top of the other wave - Unit of measurement is meters (m)
the number of waves per second Unit of measurement is Hertz (Hz)
Speed is constant for every type of EM wave: 3x10 8 m/s It is the same, always, so c is used to represent the speed of light in an EM wave
Each way of thinking about the EM spectrum is related to the others in a precise mathematical way.
Wavelength = speed of light frequency l = c f C = Speed of light = 3.0 x 10 8 m/s Why do we use c in the formula? Because photons travel at the speed of light!
Relationship is inversely proportional What happens to the frequency ( ) if the wavelength (l) is increased? What happens to the frequency ( ) if the wavelength (l) decreases?
Given one characteristic (f, l ), you can determine the other.
Medium Speed
EM waves don t need a medium (atoms) to travel through, they can travel in a vacuum (nothing!) Sound waves through air and water Seismic through Earth
EM waves travel at the speed of light, 3x10 8 m/s Speed of the waves are constant, always the same Physical waves (seismic and sound) Speed is variable and is related to frequency and wavelength V is used as to represent speed, unlike c in EM waves λ = f/v
An EM wave has a frequency of 10 Hz, what is its wavelength? An EM wave has a wavelength of 100 meters, what is its frequency? A sound wave has a frequency of 10 Hz and a speed of 15 m/s, what is its wavelength?
Stars emit electromagnetic radiation that depends on: What the stars are made of The star s temperature The star s pressure Whether the stars are moving away or towards us
Each element in the universe has its own unique spectrum of radiation that it emits Star s emit different waves of depending on what they are made of We can see these waves and determine what the star is made up of.