Radio Waves 1a. Describe frequency and wavelength 1b. What is the wavelength of radio waves defined as?

Size: px

Start display at page:

Download "Radio Waves 1a. Describe frequency and wavelength 1b. What is the wavelength of radio waves defined as?"

Kevin Gilmore
5 years ago
Views:

1 Radio Waves 1a. Describe frequency and wavelength wavelength of radio waves defined as? Longest wave lengths Lowest frequencies Wave length: 1meter to 10km for terrestrial communication radio Cosmic radio waves might not have an upper limit to length 1c. Broadcast waves are used by what two common devices? This signal is converted to what two types of information? Radio stereos T.V. Sound &/or images 1d. How are microwaves related to radio waves? They overlap in terms of wave lengths. Some microwaves could be considered radio and vice versa. 2. What are the steps in a radio transmission? List & describe at least 4. Pg367 and Fig Sound (music or voice) must first be transformed from sound waves into radio waves. Microphone associated electronic recording device. 2. Next this must be modified (modulated) into the radio station s carrier wave. Ex: WRWV Electrons are vibrated in the stations antenna, the wave is transmitted over the airways. 4. Electrons in your car s antenna vibrate and electronic convert this signal back into sound waves by vibrating a speaker. 3. Explain the difference between AM and FM radio waves. Fig 16 draw a picture too What does AM & FM stand for? AM Radio - Amplitude modulation (modification) It looks like a Cardiograph of someone heart beating sort of. The changing amplitude is what is encoding for the information being sent. FM Radio - Frequency modulation (modification) The changing frequency is what is encoding for the information being sent. 4. List all the waves involved in the use of a cell phone? Why is it called a cell phone? Explain Pg371 Sound waves Radio waves Micro waves One radio waves frequency for sending Another radio wave frequency for receiving Base stations or (microwaves cell towers) same thing Are located several kilometers apart. Further in rural area closer in urban area dependent on how many cell phone users. The geographic area that the particular cell tower services is referred to as a cell. Your personal cell phone always initially sends a signal to the same cell tower when at home. 5. Why do some satellites use microwaves over radio waves? What do they do to the broadcasted freq? Why do they change frequency & amplitude? Pg372 The shorter wave lengths of microwaves help to travel through the atmosphere more effectively. A TV or radio station broadcasts a higherfrequency signal to a satellite. The satellite must then amplifies it while retransmitting down to earth so that it can cover a large region and lots of end users all over. Think about it. A satellite is one fixed point up in the sky. No need to broadcast with high amplitude. However, the transmitted signal back down to earth needs to be broadcast to thousands of people and their phones, radios or TV so the amplitude has to be high! 6. Why is it advantageous to have a geosynchronous satellite? Geosync means to orbit at the same speed as earth s rotation. If you orbit at the same speed you can stay over the same region indefinitely or at least as long as the life of a particular satellite. In this way a particular region never losses the broadcast signal coming back down to earth. Think about it. We have 24/7 news, media and telecast. This wasn t always the case before satellites. A geosynchronous satellite means less loss of cell signal or GPS signal as satellites move out of range. They stay fixed overhead. 1

Microwaves 1A. What is the difference between a microwave and radio wave. Define/discuss wavelength. Pg1- pg360 2. List 5 things microwaves are used for other than microwave ovens. 3.

What role do microwaves play in phones? Discuss the tower in figure 20 - What type of tower is it? What does a microwave antenna look like? sketch 6. What is GPS? Which wave does it use?

2 Microwaves 1A. What is the difference between a microwave and radio wave. Define/discuss wavelength. Pg1- pg List 5 things microwaves are used for other than microwave ovens. 3. Describe/discuss how a microwave oven heats your food. What does it do to water molecules? pg What are three steps and three components of microwaves? What does each component do? pg5 5. What role do microwaves play in phones? Discuss the tower in figure 20 - What type of tower is it? What does a microwave antenna look like? sketch 6. What is GPS? Which wave does it use? What does it stand for? How does it work? Elaborate What happens if GPS Fails? Describe 4 things Elaborate Microwaves have overlapping wave length with radio waves. In general they have shorter wavelength than radio and longer than infrared nanometers average 1B. Range of Frequencies Microwaves actually overlap or have the same wavelength and frequency as what 2 other types of waves. Radio and infrared GPS RADAR Telephones Cellphones Pagers Communication Satellites TV The primary means by which food is heated by microwaves is through the absorption of the heat by water molecules. Is the food moist? Then it has water within. Because water is a dipolar molecule (having both a negative and positive end) is it influenced readily by electromagnetic fields. 1. MAGNETRON Microwaves generated with an electrical current through a magnetron. The magnetron emits radiation with an antenna 2. WAVEGUIDE A waveguide then directs the radiation to the oven compartment 3. STIRRER Exiting the waveguide the microwave radiation is scattered evenly about the oven with a fan (the stirrer) so that food heats evenly. Microwaves transmits phone calls, text messages and pictures on your cell phone. This is a microwave tower that services all the cell phones in a given geographic area. The cell refers to that limited area or region. Global Positioning System It is used for navigating, locating and references ones position on earth. It uses microwaves and a network of satellites. There a series of ground stations and some 24 interconnected satellites much of which are owned and operated by the United States DOD & U.S. Air Force. 1. Police, fire and EMS radio equipment could fail. 1C. Draw this: A lot of friction can be generated with little energy. A microwave antenna look nothing like your typical whip antenna. They are large cylindrical flattened drum shaped objects. 2. Banks and ATM machines stop functioning properly. 3. Parts of the electrical power grid go down. 4. Global telecommunicate networks suddenly fail 2

3 Infrared Waves 1a. Describe frequency and wavelength 2. What are two things you commonly use infrared for? What can infrared images be used for? Pg362 and Fig 11 3a. Viper Zone When and how can these snakes hunt that other predator can t? 4. How does a remote control work Explain 5. What is a Stinger Missile? How does it track a target? 6a. What was IRAS? Infrared Astronomical Satellite wavelength of infrared defined as? 1mm to mm Wavelength is between micro and visible light waves. Frequency higher than microwaves. 1c. What are the images that an infrared camera produces? Thermogram 1d. What can these be used for? Firefighters can locate victims or the hottest part of a structure fire rapidly. 1e. What other name does infrared go by? Hint we studied earlier this year. Radiant 2a. Two things: TV Remote Control CD-ROM 2b. Two things Infrared Images are used for? Earth images Vegetation Cities 2c. What is something else we could use these types of satellite infrared images for? Elaborate Produce images to analyze land use practices of developing towns, cities nations. Infrared can reveal things that typically light images do not. 3a. Viper Zone They can hunt in total darkness with pits located adjacent to their nostrils. They see sense heat energy. 3b. How and why might police or military use infrared? Elaborate With infrared cameras or goggles they can see victims or track criminals in the dark of night. Explain It used infrared heat waves to change the channel How might you conduct a little experiment with a mirror? Bounce the signal off a mirror and try to change the channel. Why does the mirror work and not some other material? Most other materials tend to absorb not reflect infrared. Explain - Mention at least 3 things it needs to work. Shouldered fired missile. 20 pound flying robot. Infrared cameras onboard guide the missile to a heat signature (coming from an aircraft s exhaust.) What other electromagnetic energy waves does it take advantage of? UV to distinguish between friendly verses foe aircraft. 6b. Why does the telescope need to be chilled? So that its own heat does block the heat signature. 6c. Why do you suppose it needed to be in orbit? To be above the atmosphere. Much of the cosmic infrared is blocked by our atmosphere. 6d. List the discoveries it was credited with? It doubled the number of known infrared sources. & Discovered 6 new comets. 3

4 Ultraviolet Rays 1a. Also sometimes called a Black light Describe frequency and wavelength 2. UV useful or harmful? Pg363 Both 3a. Examine the image on pg 364 Ozone is O3 (3) Oxygen bound together Ozone blocks UV 4. List the other harmful effects of UV? A bad sun can cause: 5. Specialized Microscopes 6a. What special ability do these frogs have? wavelength? In between visible and x-rays. 1c. Its known range of frequencies is very close in size to & similar to what other wave just opposite colored light? Violet 1d. What are the two types of ultraviolet? UVA Rays Longer UVB Rays Shorter 2a. Two health risks it causes: Skin cancer Skin damage 2b. Two health benefits? Enables your body to assimilate vitamin D needed for healthy bones and teeth. 2c. What are two useful uses of artificial UV light? Killing bacteria sterilizing instruments Fluorescent detection 2d. Pick one & explain how it is used? Bacteria killed for medical purposes Crime fighting CSI Fluorescent powder help detect finger prints and other bodily fluids. 3b. What does UV do to a CFC molecule? Breaks off a chlorine atom 3c. What does the chlorine atom do to ozone? This reacts with oxygen breaking apart O3 (ozone) 3b. What would happen without ozone? pg5 The ozone absorbs much of the sun s harmful UVB rays before they reach earth s surface. 4a. List Chills Dizziness Fever or weakness 4b. You can be burned on a cloudy day? How can this be? Yes, because shorter UV rays pass through cloud cover 4b. What does SPF stand for? How does sun screen work? Sun protection factor. It blocks or filters the harmful rays. 5a. Why do you suppose UV light microscopes can pick up finer details than light microscopes? Explain The UV waves are smaller, so they aluminate/ detect smaller things. Once a photomicrogram of the UV is printed we can then look at that. 5b. What organism can see ultraviolet? What do they use it for? Bees can see in the ultraviolet spectrum and they use it to navigate even on a cloudy days to and from the hive to help locate pollen sources. It also helps them find red flowers. 6b. How was it discovered? What happens when you shine UV on fluorescence? UV or black lights tend to make fluorescent things glow. These frogs glow even without the aid of a black light. 6c. What is so unique about this discovery? Black light amplifies the glowing First fluorescent amphibian ever discovered. 6d. What might we discover in the future? There are probably more fluorescent glowing frogs out there. UV lights can help biologist find them. 4

5 X- Rays 1a. Describe frequency and wavelength Pg x rays Pg X- Ray Vision 4. World Book - 5. Uses of X-Rays 5a. List industries Steel manufactures Computer Chips Airports Dentists and doctors 6. Characteristics & How they are produced? wavelength? Shorter than UV longer than gamma 0.01nm to 10nm 1c. What can too much exposure cause? Cancer 1d. What kind of matter blocks x-rays? Denser matter Lead aprons or your bones but not soft tissue. 2a. What other industries use x-rays? List 2-3 Steel manufactures Computer Chips Airports Dentists and doctors 2b. Explain how they are used by one of these industries and why this is important. Steel needs to be inspected for quality insurance Computer chips are inspected likewise Airports screen baggage for bombs or weapons 2c. What wave type do they overlap frequencies with? UV & Gamma 3a. What does Hugh Turvey use x-rays for? Artwork photography but with x-rays 3b. Why take pictures with x-rays? To reveal what we cannot otherwise see 3c. Are harm x-rays always harmful? Not necessarily. In fact, the medical benefits far outweigh the costs and medicine is even still now working to improve the safety of x-rays on humans. 4a. Why are they called x-rays? X originally it simply stood for unknown. Named so by the German scientist Roentgen. 4b. What is the relationship between wavelength, frequency and energy? Wavelength and frequency are inversely related. Increasing frequency means decreasing wavelength and also increasing energy. 5b. What can they tell us about crystals, enzymes or proteins? They tell us about the atomic arrangement of atoms within. With x-rays we can know more about how a crystal is built or the recipe for a protein. 5b. What emits x-rays in space? What might x-rays reveal about these things? Extremely hot objects Clouds of gas Galaxy centers Supernovas For one thing temperature of these remote objects 6a. Why is lead used at the dentist s office? Why lead specifically? Elaborate Lead absorbs more x-rays because of it extremely high density due to its very high atomic number 82. 6b. How are x-rays produced artificially? Give 3 details? Elaborate With x-ray tubes Accelerate a beam of electrons Then direct this electron stream in to a solid metal target The target then emits radiation, some in the form of x-rays. 5

6 Gamma Rays 1a. Describe frequency and wavelength Pg Gamma Pg Gamma cont. 4. Death Star - What is the most intense form of radiation in universe? Pg Death Star 2 Puzzles Pg NASA Launch 2007 GLAST Gamma Ray Large Area Space Telescope wavelength? Smallest wave length Highest frequency 1c. What are the 3 types of nuclear radiation? Alpha Beta Gamma 1d. How is gamma radiation different? This is not a particle but rather most definitely a wave. They have no charge & no mass.. 2a. What is required to stop a gamma ray? Thick blocks of lead or concrete are needed to stop it. 2b. Where do they come from? How are they produced? They come from the nucleus of radioactively decaying atoms 2c. List medical uses Can be used to kill cancer cells radiation therapy Can also be injected to produce images of the inside of your body vascular, lymphatic, circulatory system etc. 2d. Describe the weirdest medical use? How does it work? To examine inside the body, you can be injected with gamma ray emitting dyes that circulate around the body. Images than can then be produced revealing what is going on inside. 3. What wave type do they overlap frequencies with? x-rays 4a. Where do they come from? What s the leading theory? Gamma ray bursts from collapsing / colliding red giant stars Supernovas 4b. How do we find them? SWIFT a once really fast satellite with gamma detecting sensors. 4c. Is this a fast satellite? Why do you think so besides the name of course? It circled the globe every 90 minutes 5a. Why do scientists suppose the energy is not emitted in all directions? Because it so intense and we don t see them all that often. 5b. Unlikely but what could one do to earth? It could destroy the ozone layer all at once if close enough 6a. How does GLAST work? What 2 instruments does it have? Large area telescope to scan the entire the night sky and detect gamma ray bursts wherever they might be hiding 6b. What does a gamma ray do that seems to violate the Law of Conservation of Matter? Gamma rays have so much energy when they strike a tungsten plate that they actually produce an electron and a positron seemingly out of thin air. Energy becomes matter! Cool! 6c. What might we discover in the future? 3 things The source of gamma rays many is unknown Nature of black holes Dark Matter Dark Energy 6

Which type of electromagnetic wave has a wavelength longer than that of yellow light? A. Infrared radiation C. X-rays B. Gamma Rays D.

Which type of electromagnetic wave has a wavelength longer than that of yellow light? A. Infrared radiation C. X-rays B. Gamma Rays D. UV Rays Science Starter! 10.14-15.13! THE UNIVERSE AND ELECTROMAGNETIC