# Electromagnetic%20Waves - PowerPoint PPT Presentation

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## Electromagnetic%20Waves

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### Electromagnetic Waves Section 1 What are electromagnetic waves? A. Electromagnetic waves are made by vibrating electric charges and can travel through space. – PowerPoint PPT presentation

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Title: Electromagnetic%20Waves

1
Electromagnetic Waves
• Section 1 What are electromagnetic waves?
• A. Electromagnetic waves are made by vibrating
electric charges and can travel through space.
• B. Electric and magnetic fieldsrelated forces
that operate even in empty space
• 1. A moving electric charge creates a magnetic
field.
• 2. Changing magnetic fields create changing
electric fields and vice versa.

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3
Electromagnetic Waves
• C. Electromagnetic waves are produced when an
electric charge is vibrating.

4
Electromagnetic Waves
• D. Properties of electromagnetic fieldscarry
• 1. Frequency and wavelengthas frequency
increases, wavelength decreases
• a. Frequency is the number of vibrations per
second measured in hertz.
• b. Wavelength is the distance from one crest to
another and is measured in meters.
• 2. Wave speedin the vacuum of space, 300,000
km/s electromagnetic waves slow as they travel
through matter.

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Electromagnetic Waves
• E. Waves and particles difference not clear
• 1. Light can behave as a particle, a photon,
whose energy depends on frequency.
• 2. All particles can behave like a wave

7
Electromagnetic Waves
• Section 2 The Electromagnetic Spectrum
• A. The entire range of electromagnetic wave
frequencies is called the electromagnetic
spectrum.

8
Electromagnetic Waves
• B. Radio waveslow-frequency electromagnetic
waves with wavelengths from less than a
centimeter to about 1000 meters
• 1. Microwavesradio wave lengths of about 1 to 10
cm
• 2. Radarradio waves bounced off an object to
determine its speed and location
• 3. Magnetic Resonance Imaging (MRI)radio waves
produce an image of the inside of the body

9
Electromagnetic Waves
• C. Infrared waveselectromagnetic wave with a
slightly higher frequency than radio waves
people feel it as thermal energy or warmth
• D. Visible lighthas wavelengths between about
390 to 770 billionth of a meter can be seen with
the eye

10
Electromagnetic Waves
• E. Ultraviolet waveshave frequencies slightly
higher than visible light can damage skin
• 1. Ultraviolet light can kill bacteria.
• 2. Ultraviolet light can be absorbed by some
fluorescent materials and released as visible
light.
• 3. Ozone layer above Earths surface absorbs most
of the Suns harmful ultraviolet waves.

11
Electromagnetic Waves
• F. X rays and gamma raysultra-high-frequency
electromagnetic waves that can travel through
matter, break molecular bonds, and damage cells
• 1. X rays are used to provide images of bones and
to examine suitcases at airports without opening
them.
• 2. Radiation therapy is used to kill diseased
cells.

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