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## Electromagnetic Waves

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### Electromagnetic Waves 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 ... – PowerPoint PPT presentation

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Title: Electromagnetic Waves

1
Electromagnetic Waves
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• 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.
• 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
• This spectrum includes visible light and
invisible waves
• microwaves
• infrared light
• ultraviolet light
• X-rays
• gamma rays

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Wavelength and Frequency
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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
(0.000000001 m).
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The electromagnetic spectrum includes
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• Has the longest wavelength and the lowest
frequency.
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
• 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 108 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 1010 m.
• Have the highest frequency.
• Have the most energy.
• Over exposure can be