The Electromagnetic Spectrum

1. The Electromagnetic Spectrum

2. Waves… a review • Most waves are either longitudinal or transverse. • Sound waves are longitudinal. • But all electromagnetic waves are transverse…

4. What is the electromagnetic spectrum (EMS)? • Different kinds of radiation, which is just energy that travels and spreads out as it goes. • Produced by the movement of electrically charged particles • Can travel in a “vacuum” (they do NOT need a medium

5. What does theelectromagnetic spectrum (EMS) encompass? • visible light • radio waves • microwaves • infrared rays • ultraviolet rays • x-rays • gamma rays

6. longest wavelength • lowest frequency • lowest energy These are the different types of radiation in the EMS. • shortest wavelength • highest frequency • highest energy

7. Wavelength and Frequency Wavelength = Physical size of wave Frequency = Number of waves in a given period

8. Wavelength & Frequency The shorter the wavelength… …the higher the frequency.

9. EMS Wavelength…fromshortest tolongest

10. Short wavelength…high frequency Long wavelength…low frequency

11. Energy (from highest to lowest)shorter wavelengths & higher frequency =more energy decreasing wavelength increasing increasing frequency decreasing increasing ENERGY decreasing

12. Approximate sizes of electromagnetic waves

13. This shows both the size of a wavelength and possible sources of the radiation.

14. Parts of Electromagnetic Spectrum Try: Rabbits
Meet
In
Very
UnusualeXpensive
Gardens meaning: Radio
Microwaves
Infra-Red
Visible light
Ultra-violet
X-rays
Gamma rays

15. RADIO WAVES Radio waves- Have the longest wavelength and the lowest frequency in the EMS.- They emit the least energy.Uses:*TV broadcasting*AM and FM broadcast radio*Avalanche beacons *Heart rate monitors*Cell phone signals

16. Microwavesare shorter waves with more energy.Uses:* Microwave ovens* Bluetooth headsets* Broadband Wireless Internet* Radar* GPS

17. Infrared radiation- makes our skin feel warm. Uses:* Night vision goggles* Remote controls* Heat-seeking missilesVisible light- is the only part ofthe spectrum that our eyes can see.

18. Visible light is a very small part of the electromagnetic spectrum.

19. Colors of Visible Light(from least energy to most energy) ROY G. BIV  Red Orange Yellow  Green  Blue  Indigo VioletLowest HighestFrequency Frequency

20. Ultra-violet rays- Rays from the sun can burn our skin. The ozone layer helps protect us from UV rays.Uses:* Black lights* Sterilizing medical equipment* Water disinfection* Security images on money

21. Ultra-Violet Rays

22. X-rays- are high-energy radiation that can penetrate soft tissue.Uses:* Medical imaging* Airport security* Inspecting industrial welds

23. Gamma rays- have the shortest wavelength, the highest frequency, and radiate the most energy. Radioactive materials emit gamma rays as do stars.Uses – * Food irradiation (Controlling Spoilage)* Cancer treatment (Can cause mutations in cells)* Sterilizing medical equipment

24. Wavelength & Frequency • In remote sensing, we sense and sample energy at different wavelengths and frequencies. • These different frequencies tell us different things about the object being sensed.

25. Although our eyes can directly perceive only a small portion of the electromagnetic spectrum... …we can gather more information by using other portions of the EMS

26. This chart shows how well various frequencies penetrate the atmosphere. As expected, visible light penetrates the easiest. Visible Light

27. Notice that the infrared band is very broad. This allows a wide choice of remote sensing frequencies each of which is useful for a specific purpose. . Visible Light Infrared

28. Energy that strikes the Earth’s surface can be… Reflected ENERGY Absorbed Transmitted …or all three.

29. Energy Interaction Different surfaces also reflect energy differently.