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# Electromagnetic spectrum

## on Sep 14, 2010

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## Electromagnetic spectrumPresentation Transcript

• Waves of the Electromagnetic Spectrum Blue - Highlight it
• 1. Wave Properties
• Crest: the highest point of a wave.
• Trough: the lowest point of a wave.
• Rest Line (Equilibrium): the mid-point position of the wave (the dotted line).
• 1. Wave Properties
• D. Amplitude: a measure of how high the crest is (or how low the trough is); measured from the rest line.
• 1. The greater the amplitude, the more energy a wave carries.
• 1. Wave Properties
• E. Wavelength: the distance from one point on a wave to the corresponding point on the next wave.
• 1. Wave Properties
• F. Frequency: number of wavelengths passing a given point per second.
• Longer wavelengths equal smaller frequencies .
• Shorter wavelengths equal larger frequencies .
• 2. Mechanical Waves A. use matter to transfer energy; travel faster when atoms are closer together
• B. Transverse wave: wave energy causes matter in the medium to move up and down OR back and forth at right angles (perpendicular) to the wave.
• C. Compressional wave: Matter in the medium moves forward and backward in the same direction as the wave.
• Sound waves.
• AKA Longitudinal Waves.
• 3. Electromagnetic Waves
• Can transfer energy WITHOUT using matter.
• Produced by electrically charged particles.
• C. Travel faster when fewer atoms are present:
• Vacuum: 300,000 km/s
• Air: slightly less than 300,000 km/s
• Water: 226,000 km/s
• Glass: 200,000 km/s
• Diamond: 124,000 km/s
• 4. Radio Waves A. Low-frequency electromagnetic waves with wavelengths from less than 1 cm to about 1,000 m.
• By measuring the time required for radio waves to bounce off an object and return to the receiver, speed and location of the object can be found.
• Used by law enforcement and air traffic controllers.
• 2. MRI: Magnetic Resonance Imaging
• Radio wave energy causes protons in the body to react and release energy.
• The energy is detected by a receiver that maps the tissues and creates a picture of the inside of the body.
• 5. Radio Waves in Space
• Objects in space such as stars, galaxies, and nebulae emit electromagnetic radiation in the form of radio waves.
• Radio astronomers use large radio telescopes to collect the radio waves and study the data collected.
Image of Carbon Monoxide gas (CO) in the Milky Way Galaxy.
• 6. Visible Light
• The range of electromagnetic waves that you can detect with your eyes.
• Length varies from 390 billionths to 770 billionths of a meter.
• The color we see is the one being reflected .
• Red has the longest wavelength.
• Violet has the shortest.
• When all colors are being reflected , we see white .
• When all colors are being absorbed , we see black .
• 7. Visible Light in Space
• Satellite data is used to create true-color and false-color images of objects in space.
• True-color : created using red, green, and blue light waves that are reflected off the surface.
• False-color : created from data collected about the brightness of the light waves that are being reflected.
True color False Color Planet Uranus
• 8. Microwaves
• Microwaves range from 1 meter to 1 millimeter and therefore overlap the Radio wave band.
• Microwaves are good for transmitting information.
• they can penetrate haze, light rain and snow, clouds, and smoke.
• C. Scientists use microwaves to look for evidence of how the universe began.
• In the 1960's scientists discovered cosmic microwave background radiation.
• This radiation, which fills the entire Universe, is believed to be a clue to its beginning, something known as the Big Bang.
• 9. Infrared Waves
• Infrared light lies between the visible and microwave portions of the spectrum.
• thermal
• shorter ones are the size of cells, or are microscopic.
• TV remote controls
• B. Infrared radiation is great for studying cloud structure.
• Shows more cloud detail than standard pictures.
• C. Satellites have instruments that measure and record infrared radiation.
• 10. Ultraviolet Waves (UV)
• UV waves are shorter than visible light; therefore, have a higher frequency.
• Not visible to the human eye.
• Have enough energy to enter skin cells and cause cell damage, even cancer.
• Earth’s atmosphere (ozone layer) blocks most, but not all UV.
• Useful in killing bacteria.
• Can make some material fluoresce; used by Police to find seemingly hidden evidence.
• 11. X-Rays
• X-rays have smaller wavelengths and therefore higher energy.
• X-ray light tends to act more like a particle than a wave. They either pass through or are absorbed by the materials.
• Black holes, neutron stars, binary star systems, and supernova remnants all emit X-rays.
• X-Rays are blocked by the atmosphere & must be studied from space.
• 12. Gamma Rays
• Gamma-rays have the smallest wavelengths and the most energy of any other wave in the electromagnetic spectrum.
• Waves are generated by radioactive atoms and in nuclear explosions.
• Gamma-rays are produced by:
• violent events such as supernova explosions
• less dramatic events, such as the decay of radioactive material in space.
• Electromagnetic Spectrum