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Understanding Electromagnetic Waves and Their Properties

Explore the differences between electromagnetic waves and mechanical waves. Learn about the members of the electromagnetic spectrum, including examples and uses. Investigate the behaviors of light, including reflection, refraction, and diffraction.

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Understanding Electromagnetic Waves and Their Properties

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  1. S-58 How are electromagnetic waves different from mechanical waves? List four members of the electromagnetic spectrum. Two examples are light and radio waves.

  2. SPS9 Students will investigate the properties of waves Recognize that all waves transfer energy Relate frequency and wavelength to the energy of different types of electromagnetic waves and mechanical waves. Compare and contrast the characteristics of electromagnetic and mechanical (sound) waves. Investigate the phenomena of reflection, refraction, interference, and diffraction. Chapter 18 The Electromagnetic Spectrum and Light

  3. How are electromagnetic waves different from mechanical waves? What is the maximum speed of light? How do electromagnetic waves differ from one another? What is the dual nature of electromagnetic radiation? What happens as light travels farther from its source? 18.1 Electromagnetic Waves

  4. 18.1 Electromagnetic Waves How are electromagnetic waves different from mechanical waves? • Electromagnetic Waves – transverse waves that have a changing magnetic field and a changing electric field • Produced when an electric charge vibrates • Do not need a medium • Transfer of energy by electromagnetic waves is called electromagnetic radiation (EMR)

  5. 18.1 Electromagnetic Waves What is the maximum speed of light? Porsche 918 Spyder Plug in Hybrid 98 mpg 198 mi/hr (0.055 mi/s) • All electromagnetic waves travel at 300,000,000 m/s in a vacuum • Maximum speed in the universe • Goes slower in other media • 186,000 mi/s

  6. 18.1 Electromagnetic Waves How do electromagnetic waves differ from one another? v=fl • Electromagnetic waves still follow the wave equation • The speed is always 300,000,000 m/s • For vacuum – really close for air too, so we use the same number • If frequency increases, then wavelength decreases

  7. 18.1 Electromagnetic Waves What is the dual nature of electromagnetic radiation? • Electromagnetic waves sometimes behaves like a wave and sometimes like a stream of particles • travels through a vacuum – particle because waves need a medium • Light refracts – wave because particles don’t bend their path as they change mediums • Einstein – photons – wave packets of energy

  8. S-60 How do electromagnetic waves differ from one another? A. What is the speed of light in a vacuum? B. If a light beam has a wavelength of 6.33x1011 m, what is the frequency?

  9. What waves are included in the electromagnetic spectrum? How is each type of electromagnetic wave used? 18.2 The Electromagnetic Spectrum

  10. 18.2 The EM Spectrum What waves are included in the electromagnetic spectrum? • Infrared • Visible Light • Ultraviolet • X-Ray • Gamma The electromagnetic spectrum includes many waves – the following are listed in order of increasing frequency, decreasing wavelength, and increasing energy. Radio TV Microwaves Radar

  11. 18.2 The EM Spectrum How is each type of electromagnetic wave used? • Radio Waves • Radio signals • TV signals • Microwaves • Cooking, for a short frequency range • Cell phone transmission • Radar (RAdio Detecton And Ranging) • Bounce off the object for distance • Can tell speed using the Doppler Effect

  12. 18.2 The EM Spectrum How is each type of electromagnetic wave used? • Infrared Rays • Transfer heat • Sensed by heat sensors in your skin • Visible Light • The range that human eyes can detect • ROY G BIV (red, orange, yellow, green, blue, indigo, violet)

  13. 18.2 The EM Spectrum How is each type of electromagnetic wave used? • Ultraviolet • Sterilizing items • Required to form vitamin D • Tanning and skin cancer • X-Ray • Medical and safety • Can also cause cancers

  14. 18.2 The EM Spectrum How is each type of electromagnetic wave used? • Gamma Rays • Cancer treatment • Industry to check pipes • We are constantly bombarded by Gamma rays from the sun

  15. S-61 What waves are included in the electromagnetic spectrum? List 6 members of the EM spectrum in order of increasing energy.

  16. S-62 What waves are included in the electromagnetic spectrum? List 6 members of the EM spectrum in order of increasing wavelength.

  17. What three types of materials affect the behavior of light? How does light behave when it enters a new medium? 18.3 Behavior of Light

  18. 18.3 Behavior of Light What three types of materials affect the behavior of light? How light behaves when it strikes an object depends on the material the object is made of Transparent – allows most of the light to pass through it Translucent – allows light to pass through, but scatters the light Opaque – either reflects or absorbs the light that strikes it

  19. 18.3 Behavior of Light How does light behave when it enters a new medium? • A number of things can happen to light when it strikes a surface • Reflection – the light waves bounce of the surface • Regular reflection – rays bounce off in an orderly patter • Creates an image • Diffused reflection – no pattern • Only color

  20. 18.3 Behavior of Light How does light behave when it enters a new medium? • Refraction – bending of light when it strikes a surface • Cause objects to look broken • Or even a mirage (light bending due to different temperature layers of air) • Polarization – when light only vibrates in one plane • Reduces glare

  21. 18.3 Behavior of Light How does light behave when it enters a new medium? • Diffraction – bending of light around barriers • A hole will act like a new source of the wave • Ripple away from edge

  22. What determines the color of an object? What are the primary colors of light? What are the primary colors of pigments? 18.4 Color

  23. 18.4 Color What determines the color of an object? • Color depends on • What the object is made of (what colors it will absorb or reflect) • The color of light that strikes the object

  24. 18.4 Color What are the primary colors of light? • Primary colors – three specific colors that combine to create all possible colors • Red, Blue, Green (RBG) • These colors combine to form the secondary colors • Yellow, Cyan, Magenta • The primary colors all combine to form White

  25. 18.4 Color What are the primary colors of pigments? • Pigment – a material that absorbs light • Paint • Primary pigments are Cyan, Magenta, & Yellow • Ink cartridge colors • They mix to form Black

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