1. Chapters 17 & 18 The Electromagnetic Spectrum
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:

5. 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

6. So does light travel as a wave or 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.

7. 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

8. 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

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

10. Wavelength Size Comparison

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

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

13. 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”

14. Electromagnetic Spectrum and Radiation

15. 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

16. 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

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

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

19. 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 Y G B I V)
Largest to Smallest Wavelength

20. 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

21. 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

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

23. 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

24. 1A. A transverse wave that transfers electrical and magnetic energy.
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.