electromagnetic spectrum. song the electromagnetic spectrum song
TRANSCRIPT
ELECTROMAGNETIC SPECTRUM
Song
• The electromagnetic spectrum song
Brief review:
Water and sound waves transfer energy from one place to another- they require a medium through which to travel. They are mechanical waves.
Electric field-region in which charged particles can be pushed or pulled.
• The theory of electromagnetism explains that electricity and magnetism are closely related.
• Electric charges are the source of electric fields.
• Moving charges generate magnetic fields.
• Waves are the propagation of a disturbance.
• They transport energy and momentum but do not transport matter.
Video
• The electromagnetic spectrum 2 video
Nature of Electromagnetic Waves• They are Transverse waves without a medium. (They can
travel through empty space)• Transverse means perpendicular to the direction of the wave.
(No actual displacement of matter).• They travel as vibrations in electrical and magnetic fields.• Have some magnetic and some electrical properties to them.
• Speed of electromagnetic waves = 300,000,000 meters/second (Takes light 8 minutes to move from the sun to earth {150 million miles} at this speed.)
• When an electric field changes, so does the magnetic field. The changing magnetic field causes the electric field to change. When one field vibrates—so does the other.
• RESULT-An electromagnetic wave.
• Click here Animation: Interaction of vibrating charges
Waves or Particles• Electromagnetic radiation has properties of waves but
also can be thought of as a stream of particles.• Example: Light• Light as a wave: Light behaves as a transverse wave
which we can filter using polarized lenses.
• Light as particles (photons)
• When directed at a substance light can knock electrons off of a substance (Photoelectric effect)
DVD Video
• Earthquake DVD– Write down 3 things that you did not know.
Earthquake video notes
• P waves – primary (first waves)
• S waves – secondary (second + waves)
• Most damaged caused by S waves
• Liquefaction – ground below turns to quick sand due to vibrations and water underground.
Video
• Eureka Episode 30
Eureka Notes
• What is white light made of? All the colors combined plus IR (Infrared)
• White – reflecting all the colors and IR
• Black – absorbs all the colors and IR
• What determines what color something is? Which colors it absorbs and which it reflects. (It shows what is reflected)
B. Waves of the Electromagnetic Spectrum• Electromagnetic Spectrum—name for the range of
electromagnetic waves when placed in order of increasing frequency
• Click here (Animation—Size of EMwaves)RADIO WAVES
MICROWAVES
INFRARED RAYS
VISIBLE LIGHT
ULTRAVIOLET RAYS
X-RAYS
GAMMA RAYS
RADIO WAVES• A. Have the longest wavelengths and lowest
frequencies of all the electromagnetic waves.• B. A radio picks up radio waves through an antenna and
converts it to sound waves.• C. Each radio station in an area broadcasts at a different
frequency. # on radio dial tells frequency.• D. MRI (MAGNETIC RESONACE IMAGING)
– Uses Short wave radio waves with a magnet to create an image
MRI of the Brain
Video
• The electromagnetic spectrum – radio waves– What are three ways that radio waves are used?
AM=Amplitude modulation—waves bounce off ionosphere can pick up stations from different cities.
(535kHz-1605kHz= vibrate at 535 to 1605 thousand times/second)
+
FM=Frequency modulation—waves travel in a straight line & through the ionosphere--lose reception when you travel out of range.
(88MHz-108MHz = vibrate at 88million to 108million times/second)
+
Bands of Radio/TV/Microwaves
AM radio535 kilohertz to 1.7 megahertz
Short wave radio5.9 megahertz to 26.1 megahertz
Citizens band (CB) radio26.96 megahertz to 27.41 megahertz
Television stations, channels 2 through 6
54 to 88megahertz
FM radio88 megahertz to 108 megahertz
Television stations, channels 7 through 13
174 to 220 megahertz
AM Spectrum used in Broadcasting and WirelassSome common frequency bands
XM Satellite Radio uses microwaves
DVD
• Mapping the Earth’s surface DVD– What part of the electromagnetic spectrum do
GPS use?• GPS use radio waves in the microwave part of the
electromagnetic spectrum.
MICROWAVES
• Microwaves—have the shortest wavelengths and the highest frequency of the radio waves.– Used in microwave ovens.
• Waves transfer energy to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food.
– Used by cell phones and pagers.– RADAR (Radio Detection and Ranging)
• Used to find the speed of an object by sending out radio waves and measuring the time it takes them to return.
Video
• The electromagnetic spectrum – microwaves
• Seeing where the microwaves are… video
INFRARED RAYS• Infrared= below red• Shorter wavelength and higher frequency than
microwaves.• You can feel the longest ones as warmth on your skin• Heat lamps give off infrared waves.• Warm objects give off more heat energy than cool objects.• Thermogram—a picture that shows regions of different
temperatures in the body. Temperatures are calculated by the amount of infrared radiation given off. Therefore people give off infrared rays.
VISIBLE LIGHT• Shorter wavelength and higher frequency than
infrared rays.• Electromagnetic waves we can see.• Longest wavelength= red light• Shortest wavelength= violet (purple) light• When light enters a new medium it bends
(refracts). Each wavelength bends a different amount allowing white light to separate into it’s various colors ROYGBIV.
Video
• The electromagnetic spectrum video
ULTRAVIOLET RAYS• Shorter wavelength and higher frequency than visible
light• Carry more energy than visible light• Used to kill bacteria. (Sterilization of equipment)• Causes your skin to produce vitamin D (good for
teeth and bones)• Used to treat jaundice ( in some new born babies.• Too much can cause skin cancer. • Use sun block to protect against (UV rays)
– Sunburn can cause skin cancer
X- RAYS• Shorter wavelength and higher frequency than UV-rays• Carry a great amount of energy• Can penetrate most matter.• Bones and teeth absorb x-rays. (The light part of an x-
ray image indicates a place where the x-ray was absorbed)• Too much exposure can cause cancer
– (lead vest at dentist protects organs from unnecessary exposure)
• Used by engineers to check for tiny cracks in structures.– The rays pass through the cracks and the cracks appear dark on
film.
Video
• How x-rays work video
GAMMA RAYS
• Shorter wavelength and higher frequency than X-rays
• Carry the greatest amount of energy and penetrate the most.
• Used in radiation treatment to kill cancer cells.
• Can be very harmful if not used correctly.
Bone Scan
Using the EM waves to view the Sun
Animation—View a Galaxy at different wavelengths
• Brief SUMMARY• A. All electromagnetic waves travel at the
same speed. (300,000,000 meters/second in a vacuum.
• B. They all have different wavelength and different frequencies.– Long wavelength-lowest frequency– Short wavelength highest frequency– The higher the frequency the higher the energy.
Video
• How do your mobile phones work video
DVD
• Characteristics of waves and ocean - motion of waves DVD
Video
• Plate tectonics video
• Earthquakes Ring of Fire video
• Japan 2011 Earthquake (Youtube)
• 2004 Boxing Day Tsunami (Youtube)