1. Electromagnetic Waves

2. Electromagnetic waves are transverse waves consisting of changing electric and magnetic fields.
Energy travels in the form of waves.
They can travel in a vacuum as well as through matter.
Electromagnetic radiation-
the transfer of energy by
electromagnetic waves
traveling through matter or
across space.

3. Light, like sound and heat, is a form of energy.
The visible light we see is part of the electromagnetic spectrum.

4. Things to know…
frequency– how often a wave passes a point in a certain time interval
wavelength- the distance from one crest to the next or one trough to the next

5. The speed of light depends on the medium.

6. The speed of light in a vacuum is:
3 X 108 meters per second (300,000,000 m/sec)

7. The Electromagnetic Spectrum
Electromagnetic Spectrum- the full range of frequencies of electromagnetic radiation.
This spectrum includes visible light and invisible waves:
radio wave
microwaves
infrared light
ultraviolet light
X-rays
gamma rays

11. Wavelength and Frequency

12. Wavelength and Frequency of Light
Because the wavelength of light is so small, scientists measure it in nanometers.
One nanometer (nm) is one billionth of a meter ( m).

14. The electromagnetic spectrum includes:

15. Radio Waves Has the longest wavelength and the lowest frequency.
Uses: Radio, TV, radar, microwaves
Radar: radio detection and ranging, a system that uses reflected radio waves to determine the velocity and location of objects

16. Microwaves Microwaves are used in cooking and communication.
Microwaves have wavelengths in the range of centimeters.

17. Infrared Rays Wavelength smaller than radio.
slightly longer than red visible light.
felt as warmth
Used as a source of heat/or to detect heat differences.
Thermograms-
color-coded pictures
that show variations
in temperature.

18. Visible Light
Each wavelength in the visible spectrum corresponds with a specific frequency and a specific color.
Light enables people
to see, keeps people
safe and helps them
to communicate.

19. Ultraviolet Rays
Shorter wavelength and higher frequency than violet light.
Sunlight contains ultraviolet light.
The invisible light that lies just beyond violet light falls into the ultraviolet (UV) portion of the spectrum.

20. X-Rays Have very short wavelengths.
Less than 10–8 m.
Used in medicine, industry and transportation by making pictures of the inside of solid objects.

21. Gamma Rays Shortest wavelength in the electromagnetic spectrum.
wavelengths shorter than 10–10 m.
Have the highest frequency.
Have the most energy.
Over exposure can be
deadly.
Used in the medical field
to kill cancer cells and make pictures of the brain, and in industrial situations as an inspection tool.