Electromagnetic waves chapter 12
Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging uses radio waves to help diagnose illness. Protons in hydrogen atoms in bones and soft tissue behave like magnets and align with the strong magnetic field.
Microwaves
Microwave create friction between water molecules. Cooking food Each water molecule is positively charged on one side and negatively charged on the other side.
wave of speed
Nothing travels faster than the speed of light.
Radar
Radar stands for- RAdio Detecting And Ranging With radar, radio waves are transmitted toward an object.
Describe the major difference between electromagnetic waves and sound waves
Sound waves require matter in order to travel; electromagnetic waves can travel where matter is not present.
Waves and Particles
The difference between a wave and a particle might seem obvious a wave is a disturbance that carries energy, and a particle is a piece of matter.
radiant energy
The energy carried by an electromagnetic wave is called radiant energy.
Why do FM radio signals tend to be clearer than AM signals?
The strength of FM waves is kept fixed, but AM signals are amplitude modulated signals and vary in strength.
Wavelength and Frequency
The wavelength of an electromagnetic wave is the distance from one crest to another.
Radio Transmission
These vibrating electrons produce a changing electric current that contains the information about the music and words.
What range of electromagnetic waves can you detect with your eyes?
Visible light is the range of electromagnetic waves that you can detect with your eyes and has wavelengths from 750 billionths to 400 billionths of a meter.
Infrared Waves
When you stand in front of a fireplace, you feel the warmth of the blazing fire.
X Rays and Gamma Rays
X rays and gamma rays- waves with the highest frequencies and are high energy
What is represented by the blue lines in this figure?
a magnetic field Electrons moving in a wire are surrounded by a magnetic field.
The Global Positioning System
a system of satellites, ground monitoring stations, and receivers that determine your exact location at or above Earth's surface.
Radio waves
are low-frequency waves used for communication
Dividing the Radio Spectrum
carrier wave- specific frequency of the that a radio station is assigned
photon
electromagnetic wave a particle
Infrared Waves
electromagnetic waves that are thermal energy (Heat waves)
Cathode-Ray Tubes
is a sealed vacuum tube in which one or more beams of electrons are produced.
What are electromagnetic waves
made by vibrating electric charges and can travel through space where matter is not present Electromagnetic waves are produced when an electric charge that moves back and forth
Visible light
range of electromagnetic waves that you can detect with your eyes.
electromagnetic spectrum
range of frequencies.
Television
sound and images are changed into electronic signals. These signals are broadcast by carrier waves.
Which has the highest frequency?
visible light Visible light has wavelengths from 400 to 750 nm.
Ultraviolet waves
waves that overexposure can cause skin damage and cancer.
microwaves
waves used for communication / cooking food
What is the range of wavelengths of X-rays?
10-8 - 10-12 m X-rays are high-energy electromagnetic waves.
What is the system of satellites, ground monitoring stations, and receivers that can determine your exact location at Earth's surface?
A Global Positioning System uses signals from orbiting satellites to determine the receiver's location
What is a carrier wave?
A carrier wave is the specific frequency of the electromagnetic wave that a radio station is assigned.
AM Radio
AM radio stations vary the amplitude of the carrier wave AM = Amplitude Modulation
The Ozone Layer
About 20 to 50 km above Earth's surface in the stratosphere is a region called the ozone layer. Ozone is a molecule composed of three oxygen atoms
wave of speed
All electromagnetic waves travel at 300,000 km/s in the vacuum of space. ("Speed of light.")
Properties of Electromagnetic Waves
All objects emit electromagnetic waves Wave frequency increases as the temperature of the material increases
What are electromagnetic waves
An electromagnetic wave is a transverse wave.
Telephones
Cell phones use a microphone to create radio waves that are transmitted to and from a cell phone tower.
Telephones
Cell phones use a transceiver which transmits one radio signal and receives another radio signal from a cell phone tower.
A Range of Frequencies
Electromagnetic waves can have a wide variety of frequencies.
An electromagnetic wave is a(n) _________ wave.
Electromagnetic waves travel in directions that are perpendicular to their electric and magnetic fields.
Radio Waves
Even though radio waves carry information that a radio uses to create sound, you can't hear radio waves. A radio wave does not produce compressions and rarefactions as it travels through air.
FM Radio
FM radio stations by vary the frequency of the carrier wave. FM = Frequency Modulation
gamma rays
Gamma Rays- penetrate through several centimeters of lead.