electromagnetic waves & the electromagnetic...
TRANSCRIPT
Electromagnetic Waves &the Electromagnetic Spectrum
The Electromagnetic Spectrum• The name given to a group of energy waves that are mostly
invisible and can travel through empty space
• Longer waves have less energy
• Shorter waves have more energy and longer waves have less energy
longest wavelength shortest wavelength
Waves… a review
Most waves are either longitudinal or transverse.
Sound waves are longitudinal.But all electromagnetic waves are
transverse…
Electromagnetic waves
Produced by the movement of electrically charged particles
Can travel in a “vacuum” (they do NOT need a medium)
Travel at the speed of light 300,000 km/s
Also known as EM waves
Electromagnetic Waves• Transverse waves without a medium!• (They can travel through empty space)
Electromagnetic waves travel VERY FAST – around 300,000
kilometres per second (the speed of light).
At this speed they can go around the world 8 times in one second.
Electromagnetic Spectrum—name for the range of electromagnetic waves when placed in order of increasing frequency
RADIO WAVES
MICROWAVES
INFRARED RAYS
VISIBLE LIGHT
ULTRAVIOLET RAYS
X-RAYS
GAMMA RAYS
Notice the wavelength is long (Radio waves) and gets shorter (Gamma Rays)
RADIO WAVESHave the longestwavelengths and
lowestfrequencies of
all the electromagnetic
waves.
Types of EM Radiation
Radiowaves– lowest energy EM radiation
Global Positioning Systems (GPS) measure the time it takes a radio wave to travel from
several satellites to the receiver, determining the distance to each satellite.
Radio waves
Longest wavelength EM wavesUses:
– TV broadcasting– AM and FM broadcast radio– Heart rate monitors– Cell phone communication– MRI (MAGNETIC RESONACE IMAGING)
• Uses Short wave radio waves with a magnet to create an image
Radio waves
Longest wavelength EM wavesUses:
– TV broadcasting– AM and FM broadcast radio– Heart rate monitors– Cell phone communication– MRI (MAGNETIC RESONACE IMAGING)
• Uses Short wave radio waves with a magnet to create an image
MICROWAVES
Have the shortest
wavelengths and the highest
frequency of the radio waves.
Microwaves
Wavelengths from 1 mm- 1 mUses:
– Microwave ovens– Bluetooth headsets– Broadband Wireless Internet– Radar– GPS
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.
INFRARED RAYS
Infrared= below red
Shorter wavelength and
higher frequency than
microwaves.
Infrared Radiation
Wavelengths in between microwaves and visible light
Uses:– Night vision goggles– Remote controls– Heat-seeking missiles
VISIBLE LIGHTShorter wavelength and
higher frequency than infrared rays.
Electromagnetic waves we can see.
Longest wavelength= red light
Shortest wavelength= violet (purple) light
Visible lightOnly type of EM wave able to be
detected by the human eyeViolet is the highest frequency
lightRed light is the lowest frequency
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.
ULTRAVIOLET RAYSShorter
wavelength and higher
frequency than visible lightCarry more energy than visible light
UltravioletShorter wavelengths than visible lightUses:
– Black lights– Security images on money– Harmful to living things
• Used to sterilize medical equipment• Too much causes sun burn• Extremely high exposure can cause skin cancer
X- RAYSShorter
wavelength and higher
frequency than UV-rays
Carry a great amount of
energyCan penetrate
most matter.
X-rays
Tiny wavelength, high energy waves
Uses:– Medical imaging– Airport security
• Moderate dose can damaging to cells
Bones and teeth absorb x-rays. (The light part of an x-ray image indicates a place where the x-
ray was absorbed)
Used by engineersto check for tiny cracks in structures.– The rays pass
through the cracks and the cracks appear dark on film.
GAMMA RAYS
Shorter wavelength and higher frequency
than X-raysCarry the greatest amount of energyand penetrate the
most.
Gamma RaysSmallest wavelengths, highest energy EM
wavesUsesSterilizes medical equipmentCancer treatment to kill cancer cellsKills nearly all living cells.
Used in radiation treatment to kill cancer cells.
Can be very harmful if not used correctly.
Exploding nuclear
weapons emit gamma rays.
Brief SUMMARYA. All electromagnetic waves travel at the same
speed. (300,000,000 meters/second) in a vacuum.
B. They all have different wavelengths and different frequencies.– Long wavelength-lowest frequency– Short wavelength highest frequency– The higher the frequency the higher the energy.