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I. Electromagnetic Waves                     

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Presentation on theme: "I. Electromagnetic Waves                     "— Presentation transcript:

1 I. Electromagnetic Waves                     

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

3 ? ?

4 1. When an electric field changes, so does the magnetic field. When one field vibrates—so does the other. 2. RESULT- An electromagnetic An electromagneticwave. Click here  Animation: Interaction of vibrating charges Click here  Animation: Interaction of vibrating chargesInteraction of vibrating chargesInteraction of vibrating charges

5 A. Electromagnetic waves 1. Produced by the movement of electrically charged particles 2. Can travel in a “vacuum” (they do NOT need a medium) 3. 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)

6 Waves of the Electromagnetic Spectrum Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency Click here  (Animation—Size of EMwaves) Click here  (Animation—Size of EMwaves)—Size RADIO WAVES MICROWAVES INFRARED RAYS VISIBLE LIGHT ULTRAVIOLET RAYS X-RAYS GAMMA RAYS

7 Wave-particle Duality Light can behave like a wave or like a particle Light can behave like a wave or like a particle A “particle” of light is called a photon A “particle” of light is called a photon

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9 Radio waves Have the longest wavelengths and lowest frequencies of all the electromagnetic waves. Have the longest wavelengths and lowest frequencies of all the electromagnetic waves. Uses: Uses: TV broadcasting TV broadcasting AM and FM broadcast radio ( each channel is a different frequency) AM and FM broadcast radio ( each channel is a different frequency) Cell phone communication Cell phone communication

10 Microwaves Wavelengths from 1 mm- 1 m Wavelengths from 1 mm- 1 m Uses: Uses: Microwave ovens Microwave ovens Bluetooth headsets Bluetooth headsets Broadband Wireless Internet Broadband Wireless Internet Radar Radar GPS GPS

11 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.) 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.)

12 Infrared Radiation Wavelengths in between microwaves and visible light Wavelengths in between microwaves and visible light Uses: Uses: Night vision goggles Night vision goggles Remote controls Remote controls Heat-seeking missiles Heat-seeking missiles

13 Visible light Only type of EM wave able to be detected by the human eye Only type of EM wave able to be detected by the human eye Violet is the highest frequency light Violet is the highest frequency light Red light is the lowest frequency light Red light is the lowest frequency light

14 Ultraviolet Shorter wavelengths than visible light Shorter wavelengths than visible light Uses: Uses: Black lights Black lights Sterilizing medical equipment Sterilizing medical equipment Water disinfection Water disinfection Security images on money Security images on money

15 Ultraviolet (cont.) UVA UVB and UVC Energy Highest of UV waves Lower than UVA Health risks Extremely low risk for DNA damage Extremely low risk for DNA damage Can destroy Vitamin A in skin Can destroy Vitamin A in skin Can cause DNA damage, leading to skin cancer Can cause DNA damage, leading to skin cancer Responsible for sunburn Responsible for sunburn

16 X-rays Tiny wavelength, high Tiny wavelength, high energy waves Uses: Uses: Medical imaging Medical imaging Airport security Airport security Inspecting industrial welds Inspecting industrial welds

17 Gamma Rays Smallest wavelengths, highest energy EM waves Smallest wavelengths, highest energy EM waves Uses Uses Food irradiation Food irradiation Cancer treatment Cancer treatment Treating wood flooring Treating wood flooring

18 Using the EM waves to view the Sun AnimationAnimation—View a Galaxy at different wavelengths Animation

19 Brief SUMMARY Brief SUMMARY A. All electromagnetic waves travel at the same speed. (300,000,000 meters/second in a vacuum. 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. B. They all have different wavelength and different frequencies. Long wavelength-  lowest frequency Long wavelength-  lowest frequency Short wavelength  highest frequency Short wavelength  highest frequency The higher the frequency the higher the energy. The higher the frequency the higher the energy.


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