Electromagnetic Spectrum

1. Where does radiation come from?
1. Radioactive materials (sources), x-ray tubes, fallout (cosmic), from the ground (radium)
2. To further understand radiation we need to look at the electromagnetic spectrum, the characteristics of energy waves, quantum nature of radiation, and the relationship between mass and energy



2. First let us take a look at the Electromagnetic Spectrum
1. Referred to as waves, a frequency of energy
2. These frequencies are found in the electromagnetic spectrum
3. Electrical frequencies has a range with the low end comprising electric/radio waves and the hight end gamma and x-rays - See the types of frequencies?
4. Where is visible light?
1. It is a very small part of the electromagnetic spectrum
2. If you think about it, there is really very little that we can see when you consider the entire electromagnetic spectrum
5. Furthermore, notices where the different imaging systems as they acquire data at different points within the spectrum
6. Associated with frequency is the wave or energy wave.
1. There are many types of energy waves and their frequencies vary pending where they fall on the graph above
2. Most important to us are gamma rays
3. Very high frequencies (such as gamma and x-ray) exhibits light and particle characteristics. This is known photons of energy. If the originate from the nucleus of an atom they we define them as gamma-rays
4. The higher the frequency the more "vibrations per second" are seem within that given frequency
5. Is the quantum nature of these high frequency gammas that gives gamma rays their "light and mass" properties



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