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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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slide1

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

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
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

slide13

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”
slide15
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
slide19

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
slide20

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
slide21
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

slide22
X-Rays

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

Used to make images of bones

Dangerous in high doses

slide23
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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