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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

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

Polarized Light


Light travels as a wave

Light Travels as a Wave

The Wave Model:


Light travels as a particle

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


  • So does light travel as a wave or as a particle

    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.


    What is the electromagnetic spectrum

    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


    What is the speed at which all em waves travel

    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


    Believe it or not you are being showered all the time not by rain but by waves

    Tape in NB: Copy and Color visible light colors


    Wavelength size comparison

    Wavelength Size Comparison


    Electromagnetic radiation

    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


    Electromagnetic radiation1

    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


    Believe it or not you are being showered all the time not by rain but by waves

    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”


    Electromagnetic spectrum and radiation

    Electromagnetic Spectrum and Radiation


    Believe it or not you are being showered all the time not by rain but by waves

    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


    Do now draw and complete the chart

    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


    Microwaves

    Radio waves with the shortest wavelengths

    Used for cell phone communication and radar (radio detection & ranging)

    Used to cook food

    Microwaves


    Infrared rays

    Felt as heat

    Used in heat lamps, infrared

    cameras (thermograms)

    medicine, and remotes

    Infrared Rays


    Believe it or not you are being showered all the time not by rain but by waves

    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


    Believe it or not you are being showered all the time not by rain but by waves

    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


    Believe it or not you are being showered all the time not by rain but by waves

    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


    Believe it or not you are being showered all the time not by rain but by waves

    X-Rays

    Can pass through most matter (but not dense objects like bones)

    Used to make images of bones

    Dangerous in high doses


    Believe it or not you are being showered all the time not by rain but by waves

    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


    Hw 17 1

    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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