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G10 Science Q2- W1-2- Electromagnetic Waves.ppt
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- 2. S10FEIIa-b-47 Compare therelative wavelengths of different forms of electromagnetic waves
- 3. Electromagnetic Waves • Transverse waveswithout a medium! • (They can travel through empty space)
- 4. • They travelas vibrations in electrical and magnetic fields. Have some magnetic and some electrical properties to them.
- 5. When anelectric field changes, so does the magnetic field. The changing magnetic field causes the electric field to change. When one field vibrates— so does the other. RESULT-An electromagnetic wave.
- 6. Electromagnetic waves travel VERYFAST – around 300,000 kilometres per second (the speed of light). At this speed they can go around the world 8 times in one second.
- 7. Waves orParticles? • Electromagnetic radiation has properties of waves but also can be thought of as a stream of particles. Example: Light Light as a wave: Light behaves as a transverse wave which we can filter using polarized lenses. Light as particles (photons): When directed at a substance light can knock electrons off of a substance (Photoelectric effect)
- 8. Electromagnetic Spectrum—namefor the range of electromagnetic waves when placed in order of increasing frequency RADIO WAVES MICROWAVES INFRARED RAYS VISIBLE LIGHT ULTRAVIOLET RAYS X-RAYS GAMMA RAYS
- 9. Notice the wavelengthis long (Radio waves) and gets shorter (Gamma Rays)
- 11. RADIO WAVES Have thelongest wavelengths and lowest frequencies of all the electromagnetic waves.
- 12. Global PositioningSystems (GPS) measure the time it takes a radio wave to travel from several satellites to the receiver, determining the distance to each satellite.
- 13. A radiopicks up radio waves through an antenna and converts it to sound waves. Each radio station in an area broadcasts at a different frequency. # on radio dial tells frequency.
- 14. MRI (MAGNETIC RESONACE IMAGING) UsesShort wave radio waves with a magnet to create an image.
- 15. MICROWAVES Have the shortest wavelengths and thehighest frequency of the radio waves.
- 16. Used in microwave ovens. Wavestransfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food.
- 17. RADAR (Radio Detectionand Ranging) Used to find the speed of an object by sending out radio waves and measuring the time it takes them to return.
- 18. INFRARED RAYS Infrared= below red Shorter wavelengthand higher frequency than microwaves.
- 19. You canfeel the longest ones as warmth on your skin Warm objects give off more heat energy than cool objects.
- 20. Thermogram—a picture thatshows regions of different temperatures in the body. Temperatures are calculated by the amount of infrared radiation given off. Therefore people give off infrared rays. Heat lamps give off infrared waves.
- 21. VISIBLE LIGHT Shorterwavelength and higher frequency than infrared rays. Electromagnetic waves we can see. Longest wavelength= red light Shortest wavelength= violet (purple) light
- 22. When light entersa new medium it bends (refracts). Each wavelength bends a different amount allowing white light to separate into it’s various colors ROYGBIV.
- 23. ULTRAVIOLET RAYS Shorter wavelength and higherfrequency than visible light Carry more energy than visible light
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- 25. Too much cancause skin cancer. Use sun block to protect against (UV rays)
- 26. Causes your skin to produce vitaminD (good for teeth and bones)
- 27. X- RAYS Shorter wavelength and higherfrequency than UV-rays Carry a great amount of energy Can penetrate most matter.
- 28. Bones and teethabsorb x-rays. (The light part of an x-ray image indicates a place where the x-ray was absorbed)
- 29. Too much exposure cancause cancer (lead vest at dentist protects organs from unnecessary exposure)
- 30. Used byengineers to check for tiny cracks in structures. The rays pass through the cracks and the cracks appear dark on film.
- 31. GAMMA RAYS Shorter wavelength andhigher frequency than X-rays Carry the greatest amount of energy and penetrate the most.
- 32. Used in radiationtreatment to kill cancer cells. Can be very harmful if not used correctly.
- 33. The Incredible Hulk wasthe victim of gamma radiation.
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- 35. Brief SUMMARY A.All electromagnetic waves travel at the same speed. (300,000,000 meters/second) in a vacuum. B. They all have different wavelengths and different frequencies. Long wavelength-lowest frequency Short wavelength highest frequency The higher the frequency the higher the energy.
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