2 Section 1 What are Electromagnetic Waves? Vocabulary: electromagnetic wave; photonHow does a vibrating electric charge produce an electromagnetic wave?What properties describe electromagnetic waves?How do electromagnetic waves transfer energy?
3 What are Electromagnetic Waves? Waves are produced by something that vibrates and carry energy from one place to anotherWe learned that waves such as sound cannot move unless they have matter (or a medium) to transfer the energy throughBUT there is one type of energy that does not require matterThe electromagnetic wave is made by vibrating electric charges.They are composed of changing electric fields and magnetic fields
4 PropertiesThe vibrating electric and magnetic fields of an electromagnetic wave are perpendicular to each other (pg340). This is also a transverse wave.In a vacuum, all electromagnetic waves travel at 300,000 km/s. Light is a type of electromagnetic wave which is why its called the “speed of light”. Nothing travels faster than the speed of light.Wavelength is the distance from crest to crest and frequency (hertz) is the number of wavelengths that pass a point in a second. As frequency (f) increases, the wavelength (λ) becomes smaller.
5 Matter & Electromagnetic Waves Electromagnetic waves can make objects hot such as asphaltThis energy is called radiant energyRadiant energy makes fires feel warm and enables you to see
6 Waves & ParticlesA wave is a disturbance that carries energy; particle is a piece of matterAlbert Einstein provided an explanation to Heinrich Hertz’s experiment of creating a spark by shining light on a metal. Einstein said an electromagnetic wave can behave as a particle called a photon. A photon is a massless bundle of energy that behaves like a particle. As the frequency increases, the energy of the photon increases.
7 Section 2 The Electromagnetic Spectrum Vocabulary: radio waves, microwaves, infrared waves, visible light, ultraviolet waves, X-rays, gamma raysWhat are the main divisions of the electromagnetic spectrum?What are the properties of each type of electromagnetic wave?What are some common uses of each type of electromagnetic wave?
8 A Range of FrequenciesWide range from vibrating once each second or trillions of times each secondThe entire range of frequencies is called the electromagnetic spectrumEach section has a specific name (pg 345)Each region interacts with matter differently and the human eye only detects a small portion called visible light.
9 Radio Waves Longer than 10 cm Long wavelengths and low frequencies You hear sound when your radio changes the radio wave into a sound waveRadar: Radio Detecting And Ranging; used for trackingMRI create a map of different tissues to provide an inside picture of the patient’s body which is produced painlessly
10 MicrowavesWavelengths between 0.1 mm and 30cm but 1cm to 20 cm are used in communication such as cell phones and satellites. Most familiar with microwave ovens.Microwave ovens interact with water, which is why you have a defrost setting on the microwave because the water molecules in crystallize form cannot rotate.
11 Infrared RaysYou feel warmth from these wavelengths that range from about a thousandth of a meter to a about 700- billionths of a meterHotter objects emit more infrared waves than cooler objectsUsed by firefighters, energy-efficiency of a structure, CD-ROM drives, TV remote controls
12 Visible LightRange you can detect with your eyes with wavelengths around 700-billionths to 400-billionths of a meterVisible light only differs from radio waves, microwaves, and infrared waves by its frequency and wavelengthColor is the brains interpretation of the light absorbed by substances in the eyeShort wavelengths are violet to long such as redIf all colors are present in the same place, you see white
13 Ultraviolet WavesUV waves can enter cells making them both harmful and usefulCan cause sunburn (UVA & UVB) but some exposure is healthy because it creates vitamin D.It can disinfect food, water, medical suppliesFluoresce power to reveal fingerprintsOzone layer
14 X-RaysPenetrate skin and soft tissues but not denser material such as teeth and bones (Low doses)Used in airport screeningCan be harmful and both helpful to humans
15 Gamma Rays High frequencies and highest-energy photons Can penetrate several centimeters of leadProduced by processes that occur in the nuclei of atomsCan be focused to an area and cause cancer cells to die which unfortunately also kills healthy cells in the process
16 Section 3 Radio Comunication Vocabulary: carrier wave, modulation, analog signal, digital signal, transceiver, Global Positioning System (GPS)How are carrier waves modulated to transmit information?What is the difference between amplitude modulation and frequency modulation?What technologies use radio waves and microwaves for communication?
17 Radio TransmissionsEach radio, cell and television station uses an assigned frequency so stations don’t interfere with each other (pg 352)- AM, FM, etc.Specific frequency to which a station is assigned is called the carrier waveKnow the difference between FM and AM radiosCloser to the tower the stronger the signal; bad weather, surrounding mountains and artificial structures can interfere with radio transmissions
18 The Digital Revolution Analog signals are electric signals whose values change smoothly over timeDigital signals, started in 2009, is an electrical signal where there are only two possible values, on and off.Converter boxes
19 Telephones Used to be connected with wires Cell phones are transceivers which transmits one radio signal and receives another radio signalPagers work in a similar fashion
20 Communications Satellites Microwave signal is sent to the satellites and as a transceiver it sends pack to a particular region on EarthSatellite cell phones such as when crossing the ocean there are no towers to switch between; delay in two- way communicationsDishes uses microwaves rather than radio waves
21 GPSSystem of satellites, ground monitoring stations and receivers that determine your exact location at or above Earth’s surfaceNeed four satellites to determine the location of an object using a GPS receiverOwned and operated by USDoD but the signals sent out can be used by anyone. Pet collars, airplanes, ships, cars, etc.