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2.1 Waves and the Electromagnetic Spectrum

2.1 Waves and the Electromagnetic Spectrum. 7.6.a Students know visible light is a small band within a very broad electromagnetic spectrum. Waves and Energy. Wave- a disturbance that transfers energy from place to place Energy- the ability to do work

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2.1 Waves and the Electromagnetic Spectrum

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  1. 2.1 Waves and the Electromagnetic Spectrum 7.6.a Students know visible light is a small band within a very broad electromagnetic spectrum.

  2. Waves and Energy • Wave- a disturbance that transfers energy from place to place • Energy- the ability to do work • Disturbance is temporary- after wave is gone medium is calm again • Most waves require a medium to travel through • Medium- material a wave travels through • Examples of mediums: gases, liquids, solids • Waves that require a medium are mechanical waves

  3. Waves and Energy • A wave that doesn’t require a medium is an electromagnetic wave (example: light) • Key concept: Mechanical waves are produced when a source of energy causes a medium to vibrate • Vibration- repeated back-and-forth and up-and-down motion • When a vibration goes through a medium a wave results • Energy is needed to make a wave • When waves travel though a medium the medium does NOT travel with the waves

  4. Properties of Waves Key concept: The basic properties of all waves are amplitude, wavelength, frequency, and speed.

  5. Properties of Waves • Amplitude- maximum distance that the particles of the medium moves away from the rest position • Crest- high point of the wave • Trough- low point of the wave

  6. Properties of Waves Wavelength- the distance between two corresponding parts of the wave (example: from crest to crest)

  7. Properties of Waves • Frequency- number of complete waves in a certain amount of time • Hertz-units we use when measuring frequency • Waves travel at different speeds • Speed- far the wave travels in a given amount of time • If the medium doesn’t change the speed doesn’t change

  8. Properties of Waves

  9. What Is an Electromagnetic Wave? • Key concept: An electromagnetic wave consists of vibrating electric and magnetic fields that move through space at the speed of light.

  10. What is an Electromagnetic Wave? • They transfer energy without a medium • Electromagnetic waves- transfers electrical and magnetic energy • They are produced by charged particles • Every charged particle has an electric field surrounding it

  11. What is an Electromagnetic Wave? • Electromagnetic radiation- energy that is transferred through space by electromagnetic waves • Electromagnetic waves travel at the speed of light (about 300,000 kilometers per second) • They transfer energy through a vacuum or empty space • When light travels through a medium it travels slower

  12. What Is the Electromagnetic Spectrum? • The electromagnetic spectrum is the complete range of electromagnetic waves placed in order of increasing frequency.

  13. Videos: • Exploring Light and Color: The Electromagnetic Spectrum • Light: The Electromagnetic Spectrum

  14. What Is the Electromagnetic Spectrum? • More frequency means more energy • Radio waves- electromagnetic waves with the longest wavelengths and lowest frequencies (radio and TV) • Microwaves- electromagnetic waves with the shortest wavelengths and highest frequencies (microwaves and cell phones) • Infrared Rays- invisible heat (heat lamps)

  15. What Is the Electromagnetic Spectrum? • All electromagnetic waves travel at the same speed in a vacuum but at different wavelengths and different frequencies • As wavelength decreases frequencies increases • Waves with the longest wavelengths have the lowest frequencies • Waves with the shortest wavelengths have the highest frequencies

  16. What Is the Electromagnetic Spectrum? • Key concept: The electromagnetic spectrum is made up of radio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays.

  17. What Is the Electromagnetic Spectrum? • Visible light- small band in the broad electromagnetic wave that you can see • Main colors of visible light- red, orange, yellow, green, blue, indigo, violet

  18. What Is the Electromagnetic Spectrum? • Exposure to small amounts of ultraviolet rays can be healthy but too much can cause skin cancer • Ultraviolet rays- wavelengths just shorter than visible light • Ultraviolet rays carry more energy than visible light

  19. What Is the Electromagnetic Spectrum? • X-rays- wavelengths just shorter than visible light • Has more energy than ultraviolet rays so x-rays can penetrate most things • Dense matter (like bone or teeth) absorbs x-rays and doesn't let them pass through • Gamma rays- shortest waves, most frequency, and most penetrating • Gamma rays are used to kill cancer inside the body

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