1. Electromagnetic Waves
EQ: Why are Electromagnetic waves essential?

2. Electromagnetic Waves
You have seen waves travel in water, ropes, springs and have heard sound waves that travel through air and water.
All of these waves have something in common: they transfer energy through a medium.
Medium: material through which waves transfer energy (solids, liquids, gases)
Electromagnetic waves, however, are different.
Electromagnetic waves can transfer energy without a medium

3. Electromagnetic Waves
An electromagnetic wave is a transverse wave that transfers electrical and magnetic energy.
An electromagnetic wave consists of vibrating electric and magnetic fields that move through space at the speed of light.
Speed of light: 186,000 mi/sec or 300,000 km/sec

4. The Electromagnetic Spectrum
All electromagnetic waves travel at the same speed in a vacuum (no medium), but they have different wavelengths and different frequencies.
And just like we cannot hear all sounds, we cannot see all electromagnetic waves.
Some wavelengths are visible to our eyes (visible light), others our eyes cannot see (X-rays, radio waves, infrared rays)

5. The Electromagnetic Spectrum– Wavelength and frequency
Because the speed of all electromagnetic waves is the same (186,000 mps/300,00 mps), as the wavelength decreases, the frequency increases.
Wavelength – distance from crest to crest or trough to trough
Frequency – number of complete waves passing past a certain point in a certain amount of time.

6. The Electromagnetic Spectrum– Wavelength and frequency
Waves with the longest wavelengths have the lowest frequencies.
Waves with the shortest wavelengths have the highest frequencies
The higher the frequency, the higher the energy it is.

7. The electromagnetic spectrum
The electromagnetic spectrum is the complete range of electromagnetic waves placed in order of increasing frequency.
The electromagnetic spectrum is made up of radio waves, infrared waves, visible light, ultraviolet rays, X-rays and gamma rays

8. Radio waves
Radio waves are the electromagnetic waves with the longest wavelengths and lowest frequencies.
They include broadcast waves (for radio and television) and microwaves

9. Broadcast waves
Radio waves with longer wavelengths are used in broadcasting.
They carry signals for both radio and television programs.
A broadcast station sends out radio waves at certain frequencies
Antennas pick up the wave and converts the radio signal into an electrical signal.
The electrical signal is then converted into sound (and pictures as well on televisions)

10. Microwaves
The radio waves with the shortest wavelengths and the highest frequencies are microwaves.
Used for microwave ovens, cell phones, and RADAR.

11. Infrared rays
Infrared waves with wavelengths shorter than radio waves.
Use in heat lamps to keep food warm in restaurants, infrared cameras to help law enforcement find warm objects, and satellites in space use infrared cameras to study plant growth on Earth as well as the motion of clouds

12. Visible light
Electromagnetic waves that you can see are called visible light.
They make up only a small part of the electromagnetic spectrum.
Visible light waves have shorter wavelengths and shorter frequencies than infrared rays.

13. Visible light
Visible light waves with the longest wavelengths appear red in color.
As the wavelengths decrease, you see other colors of light.
The shortest wavelengths of visible light appear violet in color.

14. Ultraviolet rays
Electromagnetic waves with wavelengths shorter than those of visible light are called ultraviolet rays.
Ultraviolet rays have shorter frequencies than visible light, so they carry more energy.
The Sun’s rays are ultraviolet rays

15. Ultraviolet rays
The energy from ultraviolet rays is strong enough to burn your skin, cause cancer, damage your eyes or kill living cells.
Small doses are healthy for bones and teeth, as ultraviolet rays cause skin cells to produce Vitamin D

16. X-Rays
X-Rays have wavelengths just shorter and frequencies a little higher than ultraviolet rays.
Because of their high energy, X-rays can penetrate most matter.
This makes them useful to make images of teeth and bones, as the X-rays pass through the soft tissues but not the bony structures.
Too much exposure to X-rays can cause cat is why you wear a lead apron to protect your internal organs when you are having an X-ray made.
X-rays are also used to see if cracks exist in steel or concrete

17. Gamma Rays
Gamma rays are electromagnetic waves with the shortest wavelengths and shortest frequencies.
They are the most penetrating of all the electromagnetic waves.
Some radioactive and certain nuclear reactions produce gamma rays.
Gamma rays are used to kill cancer cells (radiation)

18. EQ: Why are electromagnetic waves essential?
EM Waves
EQ: Why are electromagnetic waves essential?

19. Assessment Prompt Electromagnetic waves sort
Use your GO to categorize cards to the most appropriate EM wave
Go in order from radio waves up to gamma rays
RADAR and Microwaves will each be their own category
Have Mrs. Belaski check for accuracy
Part II – EM WAVE Acrostic
Collaboratively design an acrostic for EM waves across the top of your poster
Poster board and markers are on the back counter
See board for model
Words/short phrases MUST relate to EM waves and their practical (real-life) uses
You may use your notes to assist
DON’T BE LAZY --- full thoughts for each letter
Bring to Mrs. Belaski to hang in the hall

20. Real-life Applications of the eM Spectrum
EQ: Why Are Electromagnetic waves essential?

21. Background
Electromagnetic waves are essential in regard to supporting life on Earth.
The Sun’s energy travels by way of ultraviolet rays to power our water cycle, which in turn, takes part in producing our weather, food, clothing and shelter.
In addition to life-supporting ultraviolet (UV) rays, we, as a species are dependent upon EM waves in a quest for a more satisfying life style.
Radio waves allow us to communicate
Infrared waves are used in law enforcement
Visible light waves allow us to see our world
X-rays are used by engineers to detect weaknesses in structures
Gamma rays allow us to cure disease

22. Today’s activity
Using the laptop, you will be investigating and recording how the different electromagnetic waves are used in every day life (with the exception of visible light)at the individual level
You have been given one practical application for each type of wave.
Use the laptop to find the latest technologies supporting each given application using the given electromagnetic waves.
Then, discuss the advantages of using this technology and find other uses for the application.
Then, for each wave, research and find another real-life application for each wave, research the latest technologies, discuss the advantages of using the technology and other uses for this application