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Electromagnetic Spectrum

Electromagnetic Spectrum. EM Waves. Electromagnetic waves are created by changes in electric and magnetic fields. These changes in the electric field cause changes in the magnetic field and this change causes another change in the electric field. The cycle continues. ….

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Electromagnetic Spectrum

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  1. Electromagnetic Spectrum

  2. EM Waves • Electromagnetic waves are created by changes in electric and magnetic fields. • These changes in the electric field cause changes in the magnetic field and this change causes another change in the electric field. • The cycle continues. ….

  3. Electromagnetic Waves • There are many type of EM waves. • Sometimes they are referred to as rays. • Electromagnetic Spectrum – name for the range of electromagnetic waves when placed in order of increasing frequency

  4. EM Wave Properties • All EM waves are TRANSVERSE waves • They require NO medium! • They CAN travel through empty space!

  5. EM Waves EM Waves are radiated by ALL objects. They ALL travel at the speed of light. c = 300,000,000 m/s

  6. c = 300,000,000 m/s At this speed the waves could go around the world 8 times in one second!!! How fast is that?!?!

  7. Wavespeed Formula Still Works! C = fλ

  8. The EM Spectrum

  9. Radio Waves • Have the longest wavelengths and the lowest frequencies. • A radio picks up radio waves sent out from towers and converts them into to sound waves.

  10. AM, FM and TV • AM has the lowest frequency • 535kHz-1605kHz • FM radio and TV have the highest frequency. • 88MHz-108MHz

  11. They also carry signals for your TV and cell phones. But radio waves are also emitted by other things such as stars and gases in space. Radio Waves…

  12. Microwaves • Microwaves are good for transmitting information from one place to another. • Microwaves in space are used to learn about the structure of nearby galaxies.

  13. Microwave ovens: Waves transfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food. • Microwaves can be used for remote controls and radar, too, such as the Doppler radar used in weather forecasts.

  14. Infrared • Infrared waves lie between the visible and microwave part on the EM spectrum. • Far infrared waves are thermal. • Warm objects give off more heat energy than cool objects

  15. Our skin emits infrared waves. • which is why we can be seen in the dark by someone using night vision goggles. • In space, Infrared light maps the dust between stars.

  16. Visible Light • Visible light waves are the only electromagnetic waves we can see. • Each color has a different wavelength. • Red has the longest wavelength and violet has the shortest wavelength. • When all the waves are seen together, they make white light.

  17. Remembering the Colors ROYGBIV

  18. Cones in our eyes are receivers for these tiny visible light waves. • The Sun is a natural source for visible light waves and our eyes see the reflection of this sunlight off the objects around us. • The color of an object that we see is the color of light reflected. • All other colors are absorbed.

  19. Ultraviolet • Ultraviolet (UV) light has shorter wavelengths and a higher frequency than visible light. • We know that the sun is a source of UV rays.

  20. UV Rays • Are why you use sunblock!! • They can do damage to your skin and even cause skin cancer!!! • They come in 2 types A and B

  21. UV RAYS—Uses • Used to kill bacteria and for the sterilization of equipment. • Causes your skin to produce vitamin D (good for teeth and bones) but too much can cause skin cancer.

  22. X-Rays • Shorter wavelength and higher frequency than UV-rays. • Can travel through most matter. • The Earth's atmosphere is thick enough that virtually no X-rays are able to get through from outer space.

  23. Hot gases in the Universe also emit X-rays . • Bones and teeth absorb x-rays. • Used by engineers to check for tiny cracks in structures • Used in airports to check baggage.

  24. Gamma-rays • Gamma-rays have the smallest wavelengths and the highest frequency. • Have the greatest amount of energy and pass through the most. • These waves are generated by radioactive atoms and in nuclear explosions.

  25. Radioactive materials can emit gamma-rays. • They are also produced by supernova explosions or the destruction of atoms, and the decay of radioactive materials. • Gamma-rays can kill living cells, such as cancer cells.

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