1. Electromagnetic Waves

2. Electromagnetic Waves
Made by vibrating electric charges
Can travel through space where matter is not present
We cannot hear them, but can feel and experience their effects
Vibrations of Electric Charges

3. Electromagnetic Waves
Travel by transferring energy between vibrating electric and magnetic fields
Like some mechanical waves, electromagnetic waves are considered transverse

4. Electric and Magnetic Fields
Electric Fields
Electric field surrounds all electric charges
Electric Field Lines
Magnetic Fields
Magnetic field surrounds all magnets
Magnetic Field Lines

5. Electric and Magnetic Fields

6. Making Electromagnetic Waves
Electric charges vibrate
Electric field around it changes
The magnetic field around the charge changes
Both fields change continuously creating the wave

7. Making Electromagnetic Waves
Making of Electromagnetic Wave

8. Properties of Electromagnetic Waves
All objects contain charged particles
All objects emit electromagnetic waves
Radiant Energy
Energy carried by EM waves

9. Properties of Electromagnetic Waves
Wave speed
Travel at 300,000 km/s in the vacuum of space
Called “speed of light”
Usually travel slowest in solids
Travel fastest in gases

10. Properties of Electromagnetic Waves
Wavelength and Frequency
Crest to crest
As frequency increases, wavelength decreases

11. Waves and Particles Em waves Photons Can behave like particles
This is why energy depends on frequency, not amplitude
Photons
Particles of electromagnetic waves
Carrier of electromagnetic radiation

12. Electromagnetic Spectrum
Frequency range
Wide variety of frequencies
Entire range is known as the electromagnetic spectrum

14. Radio Waves Lowest frequency on the spectrum Can’t see or hear
Functions:
Carry radio waves
Used by some cell phone towers
RADARs (Radio Detecting and Ranging)
MRIs

15. Microwaves Little shorter wavelengths than radio waves Functions
Cell phone towers
Satellite signals
Microwave ovens

16. Infrared Waves Shorter wavelengths than radio or microwaves Functions
Transmits thermal energy
Remote controls
CD-ROMs are read by infrared waves
Infrared imagery

17. Visible Light
Only part of the spectrum we can see
ROY G BIV

18. Ultraviolet Waves Can enter skin cells
Overexposure can cause skin damage and cancer
UVA and UVB waves
Functions
Kills bacteria on objects such as food or medical supplies
Make some materials fluoresce (CSI)

19. X-Rays Can penetrate skin Functions X-rays of bones and teeth
At airport to screen luggage and other devices

20. Gamma Rays Shortest wavelength of the spectrum Functions
Radiation therapy in which gamma rays kill diseased or cancerous cells

22. Radio Communication Radio Transmission
Each station assigned a certain frequency
Carrier Wave
Specific frequency of the electromagnetic wave assigned to a station

23. AM Radio AM Radio AM = amplitude modulation
Broadcasts by varying the amplitude of the carrier wave
AM carrier range from frequencies of 540,000 to 1,600,000 HZ

24. FM Radio FM Radio FM = Frequency Modulation
FM broadcasts by changing the frequency of the carrier wave
Frequencies range from 88 million to 108 million Hz