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Believe it or not, you are being “showered” all the time, not by rain but by waves.

Do Now: 2 NJ ASK Questions Make a cover page for our next unit: Light, The Electromagnetic Spectrum, & Color. The Electromagnetic Spectrum. Believe it or not, you are being “showered” all the time, not by rain but by waves. Chapters 17 & 18. popcorn cell phone. Polarized Light.

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Believe it or not, you are being “showered” all the time, not by rain but by waves.

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  1. Do Now: 2 NJ ASK Questions Make a cover page for our next unit: Light, The Electromagnetic Spectrum, & Color The Electromagnetic Spectrum • Believe it or not, you are being “showered” all the time, not by rain but by waves. Chapters 17 & 18 popcorn cell phone

  2. Polarized Light

  3. Light Travels as a Wave The Wave Model:

  4. Light Travels as a Particle The Particle Model: • Photoelectric Effect: When electrons change energy levels free electrons are produced… where does this energy go? • Energy makes the photons that produce a form of light energy. • In 1905 Einstein named the “Photon” which he called “bundles of radiation” • Won the Nobel Prize in 1921

  5. So does lighttravel as a waveor as a particle? • Since there is evidence for both, light is believed to act as both a wave and a particle. • The frequency and amount of energy in the photons are responsible for the type of energy produced.

  6. What is the Electromagnetic Spectrum? • The complete range of EM (electromagnetic) waves placed in order of increasing frequency and decreasing wavelengths. • All EM waves have different wavelengths and frequencies, but travel at the same speed. EM Spectrum Song

  7. What is the speed at which all EM waves travel? • All EM waves travel at the speed of light! • Speed of light = 299,792,458 m/s • Can be rounded to: • 300,000,000 m/s • 300,000 km/s • 186,000 mi/s

  8. Tape in NB: Copy and Color visible light colors

  9. Wavelength Size Comparison

  10. Electromagnetic Radiation • All EM waves produce some form radiation! • The lowerthe frequency, the lower the radiation. • The higher the frequency, the higher the radiation. EMS YouTube popcorn cell phone

  11. Electromagnetic Radiation • All EM waves produce some form radiation! • The lowerthe frequency, the lower the radiation. • The higher the frequency, the higher the radiation. EMS YouTube

  12. Electromagnetic Waves • Transverse-like waves that travel at the speed of light (No medium needed) • Consist of traveling electric and magnetic fields • Also contain tiny particles called photons which are “packets of light/energy”

  13. Electromagnetic Spectrum and Radiation

  14. Radio Waves Used to broadcast radio and TV signals Satellites (in space) receive waves and relay signals back to Earth AM/FM Radio, Satellite Radio/TV, GPS • AM: Amplitude changes • FM: Frequency changes

  15. DO NOW: Draw and complete the chart Electromagnetic waves travel at the speed of have different consist of Electric fields Magnetic fields Wavelengths Frequencies Light

  16. Radio waves with the shortest wavelengths Used for cell phone communication and radar (radio detection & ranging) Used to cook food Microwaves

  17. Felt as heat Used in heat lamps, infrared cameras (thermograms) medicine, and remotes Infrared Rays

  18. Visible Light • Portion of the E.M. spectrum that the human eye can see • White light is a mixture of 7 colors: • red, orange, yellow, green, blue, indigo, & violet • (R O YGB I V) • Largest to Smallest Wavelength

  19. Visible Light • Without a light source we cannot see colors! Think About it… • Have you ever seen color at night in the dark?? • A prism will refract light showing the colors of the visible light spectrum

  20. Ultraviolet (UV) Rays Frequencies just higher than visible light (violet end) Causes sun tans & burns Helps produce vitamin D Can kill cells (good for cleaning germs, bad for skin) Allows bees to see pollinated flowers Dangerous in high doses

  21. X-Rays Can pass through most matter (but not dense objects like bones) Used to make images of bones Dangerous in high doses

  22. Gamma Rays Produced by radioactive substances and nuclear reactions Used as cancer treatments Used to diagnose medical conditions Dangerous in high doses Greatest amount of energy

  23. HW 17.1 1A. A transverse wave that transfers electrical and magnetic energy. B. Travel as vibrations in electric and magnetic fields that move through space at the speed of light. C. Electric field- surrounds every charged particle and produces electric forces that can push or pull on other charged particles. Magnetic Field- produced when a charged particle moves and it exerts magnetic forces that can act on certain materials. 2A. Wave model and particle model of light B. Light strikes a polarizing filter, only some waves pass through. These waves vibrate in only one direction and are called polarized light. C. When light acts like a stream of tiny particles of energy, called photons, the photons can cause electrons to be knocked out of some substances. (Free electrons create energy) This is the photoelectric effect.

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