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I. Electromagnetic Waves. . Waves… a review. Most waves are either longitudinal or transverse. Sound waves are longitudinal. But * all electromagnetic waves are transverse …. ?. ?.
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I. Electromagnetic Waves
Waves… a review • Most waves are either longitudinal or transverse. • Sound waves are longitudinal. • But *all electromagnetic waves are transverse…
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When an electric field changes, so does the magnetic field. When one field vibrates—so does the other. • RESULT- • An electromagnetic wave. • Click here Animation: Interaction of vibrating charges
A. Electromagnetic waves • Produced by the movement of electrically charged particles • Can travel in a “vacuum” (they do NOT need a medium) • Travel at the speed of light: 300,000,000 meters/second (Takes light 8 minutes to move from the sun to earth {150 million miles} at this speed.) (Also known as EM waves)
Waves of the Electromagnetic Spectrum • Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency • Click here (Animation—Size of EMwaves) ULTRAVIOLET RAYS INFRARED RAYS GAMMA RAYS RADIO WAVES X-RAYS VISIBLE LIGHT MICROWAVES
Wave-particle Duality • Light can behave like a wave or like a particle • A “particle” of light is called a photon
Radio waves • Have the longest wavelengths and lowest frequencies of all the electromagnetic waves. • Uses: • TV broadcasting • AM and FM broadcast radio ( each channel is a different frequency) • Cell phone communication
Microwaves • Wavelengths from 1 mm- 1 m • Uses: • Microwave ovens • Bluetooth headsets • Broadband Wireless Internet • Radar • GPS
How does a microwave oven work? • 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.)
Infrared Radiation • Wavelengths in between microwaves and visible light • Uses: • Night vision goggles • Remote controls • Heat-seeking missiles
Visible light • Only type of EM wave able to be detected by the human eye • Violet is the highest frequency light • Red light is the lowest frequency light
Ultraviolet • Shorter wavelengths than visible light • Uses: • Black lights • Sterilizing medical equipment • Water disinfection • Security images on money
X-rays • Tiny wavelength, high energy waves • Uses: • Medical imaging • Airport security • Inspecting industrial welds
Gamma Rays • Smallest wavelengths, highest energy EM waves • Uses • Food irradiation • Cancer treatment • Treating wood flooring
Using the EM waves to view the Sun Animation—View a Galaxy at different wavelengths
Brief SUMMARY • A. All electromagnetic waves travel at the same speed. (300,000,000 meters/second in a vacuum. • B. They all have different wavelength and different frequencies. • Long wavelength-lowest frequency • Short wavelength highest frequency • The higher the frequency the higher the energy.