2. 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.
• The classification of
electromagnetic
waves according to
frequency.
3.
4. Nature of
Electromagnetic Waves
• They are Transverse waves
without a medium. (They can
travel through empty space)
• Energy carrying waves emitted
by vibrating charges often
electrons that is composed of
oscillating electric and magnetic
fields that generate one another.
14. • 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
Waves of the Electromagnetic
Waves of the Electromagnetic
17. Radio wave
• Your radio captures radio
waves emitted by radio
stations, bringing your favorite
tunes. Radio waves are also
emitted by stars and gases in
space.
19. • 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.
Microwaves
Microwaves
20. Microwave
• Microwave radiation will
cook your popcorn in just a
few minutes, but is also
used by astronomers to
learn about the structure of
nearby galaxies.
22. • 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.
Infrared
Infrared rays
rays
23. Infrared
• Night vision goggles pick up
the infrared light emitted by
our skin and objects with heat.
In space, infrared light helps
us map the dust between stars.
28. • 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)
Ultra
Ultra-
-violet
violet rays
rays
29. Ultraviolet
• Ultraviolet radiation is emitted by
the Sun and are the reason skin
tans and burns. "Hot" objects in
space emit UV radiation as well.
33. • 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.
X
X-
-rays
rays
34. X-ray
• A dentist uses X-rays to
image your teeth, and
airport security uses
them to see through
your bag. Hot gases in
the Universe also emit
X-rays.
41. 3-2-1 EXIT CARD
3-What have you learned
today? Explain.
2-What life lessons have you
gained from the topic?
1-What MI Activity did you
learn the most from?
