Chapter 12 Electromagnetic Waves
Pager
- a radio receiver on which a message is left
Cell Phone
- electrical signal creates a radio wave that is transmitted to and from a microwave tower
Visible light
- has wavelengths between about 390 to 770 billionths of a meter; can be seen with the eye
Ultraviolet Waves
- have frequencies slightly higher than visible light; can damage skin
Magnetic Resonance Imaging (MRI)
- radio waves produce an image of the inside of the body
Television
- sounds and images changed into electronic signals broadcast by carrier waves
Global Positioning system (GPS)
- system of satellites, ground stations, and receivers that provide information about the receiver's location on or above the Earth's surface
Cordless Telephone
- uses a transceiver to send one radio signal and receive another at a different frequency from a base unit
Radar
-Radio waves bounced off an object to determine its speed and location
Sun Block, A hat, Stay out of the sun
3 Ways to protect your self from UV rays
Moving
A _______ electric charge creates a magnetic field
Tanning Bed
A form of artificial UV radiation
Infrared waves
A remote control uses ______ to communicate with a tv set
Electron beams
A sealed vacuum chamber called a cathode- ray tube has a coated screen that receives _________ to provide images
Amplitude
AM radio stations broadcast electronic signals by varying the ________ of the carrier wave; frequencies range from 540 to 1,600 thousand vibrations per second
Particles
All ______ can behave like a wave
AM
Amplitude Modulation, radios gather waves through antenna
FM
Audio sent by ______ radio waves
Far Infrared Waves
Closer to microwave region
Blue
Color with the Shortest Wavelength
Show finger prints
Detectives use UV rays to _______
Forces
Electric and magnetic fields- related _________ that operate even in empty space
Space
Electromagnetic waves are made by vibrating electric charges and can travel through ________
Vibrating
Electromagnetic waves are produced when an electric charge is _______
Frequency
FM radio stations transmit electronic signals by varying the _______ of the carrier wave; frequencies range from 88 million to 108 million vibrations per second
HAM
FM waves originated from ________
Ionosphere
Fm waves can be reflected by the _______
Strength
Fm waves send signals with less noise and static than AM because the ______ is kept the same
FM
Frequency Modulation, can leave earth's atmosphere, signals have a hard time passing through materials that are good conductors of electricity, act like light waves
increases
Frequency and wavelength- as frequency _______, wavelength decreases
Vibrations
Frequency is the number of ________ per second; measured in hertz
higher
Infrared waves- electromagnetic wave with a slightly _______ frequency than radio waves; people feel it as thermal energy or warmth
Photon
Light can behave as a particle a _____, whose energy depends on frequency
10
Microwaves- radio wavelengths of about 1 to ______ cm
Gamma Rays
Produced by processes that occur in atomic nuclei, given off by stars and radioactive substances, produced by hottest regions of the universe
Waves
Properties of electromagnetic _______- carry radiant energy
kill
Radiation therapy is used to _____ diseased cells
Transmission
Radio _______ - radio converts electromagnetic waves into sound waves
mobile
Satellite telephone systems- ________ phones transmit radio signals to a satellite, which relays them back to a ground station that passes the call into the telephone network
Galaxies
Scientists use UV rays to study _________
Sound waves
Telephones- microphone converts _____ into electrical signal
microwaves
Television satellites- uses ______ rather than longer wavelength radio wave; ground receiver dish focuses the microwave beam onto an antenna
Carrier Wave
The _______ is the specific frequency of the radio wave to which a radio station is assigned
Ozone Layer
The __________ is 20 to 50 kilometers off the Earth's surface
Range
The entire _______ of electromagnetic wave frequencies is called the electromagnetic spectrum
dangerous to people
UV rays are
Kill bacteria, make fluorescent lights
UV rays are used to ______
Fluorescent
Ultraviolet light can be absorbed by some ________ materials and released as visible light
Bacteria
Ultraviolet light can kill __________
shorter, longer
Ultraviolet waves are ________ than visible light waves and ___ than x rays
Outward
Vibrating electric and magnetic fields travel______ from the moving charge
Surrounded
Vibrating electric charges are _______ by vibrating electric and magnetic fields
AM
Video sent by ____ signals
300,000 km/s
Wave speed - in the vacuum of space ______; electromagnetic waves slow as they travel through matter
Infrared waves
Wavelength between about 1 mm and 750 billionths of a meter, not harmful
distance
Wavelength is the ________ from one crest to another and is measured in meters
Infrared Waves
Wavelength slightly longer than what humans can see
Difference
Waves and particles- _______ not clear
Bones and Teeth
X Rays are used to provide images of _____ and to examine suitcases at airports without opening them
Short wavelength, high frequency
X rays are _________
Radios
_____ pick up vibration vibrations and change it to an electric current to move speakers
X Rays
______ and gamma rays- ultra high frequency electromagnetic waves that can travel through matter, break molecular bonds, and damage cells
Ozone
_______ is a molecule composed of three oxygen atoms
Radio
_______ waves- low frequency electromagnetic waves with wavelengths from less than a centimeter to about 1000 meters
Changing
________ magnetic fields create changing electric fields and vice versa
Fluorescent
_________ materials absorb ultraviolet waves and reemit the energy as visible light
Doctors and dentists
___________ use low doses of x rays to form images
Ozone
_______layer above Earth's surface absorbs most of the sun's harmful ultraviolet waves
radiation therapy
a technique to kill diseased cells in the human body
FM Radio waves
an electromagnetic waves that has a radio frequency between 88 to 108 hertz
Temperature, wavelength
as _______ increases _______ decreases
Give off x rays
black holes, neutron stars, binary stars, supernova remnants, the sun
mutations
can cause _______ in growing tissue, cannot be captured or reflected in mirrors
AM radio waves
can travel in ionosphere, measured in hertz, used for entertainment, music, communication,117 frequencies, could get 5,00 channels, distance depends on (soil conduction, power of transmitter, and channel)
Near infrared waves
closest to visible light region, do not produce as much heat
microwave
communication satellites- high frequency ______ signal is transmitted to a satellite, which amplifies it and returns it to Earth at a different frequency
W.C. Rontgen
discovered x rays in 1895
Gamma Rays
electromagnetic waves with wavelength shorter than 10 trillionths of a meter, highest energy, passes through anything
Infrared waves
every object emits them, Tv remotes and CDs use them
Infrared detectors
form images of objects from the infrared radiation
Vitamin D
humans need UV rays for _______
Red, white
longest wavelength, all of the colors put together
the sun
most natural UV radiation comes from _______
Infrared sensors
produce images that can help identify vegetation over a region
Microwaves
radio waves with less than 30 cm, used for communication (cell phones, satellite signals)
Visible Light
range of electromagnetic waves that protect you eyes, wavelengths are around 750 billionths to 400 billionths of a meter
Hotter
the _____ the object the more infrared waves it emits
Aurora
the earth glows by producing _______ high in the earth's atmosphere
Thermal Energy
the warmth you feel is the ______ transmitted to you
Radio Waves
type of electromagnetic waves often used for communication
X ray
wavelengths between about 10 billionths and 10 trillionths of a meter, have the 2nd shortest wavelength along with high frequencies
