how does a telephone work scientifically?
596411
The telephone operates on simple principles. A telephone mouthpiece contains a thin metallic coating separated from an electrode by a thin barrier (today we use plastic) which connects to a wire carrying an electric current. When a person speaks into the mouthpiece, the acoustic vibrations from her speech push the metallic coating slightly closer to the electrode, resulting in variations in voltage and therefore a speedy conversion from acoustic to electric energy. The electric pulses are conveyed through a wire to the speaker on the other end, where electric pulses are converted into acoustic energy again.
552588
It requires electricity. If there's a storm or blackout, VOIP  phone can't not be used.\n\nhttp://en.wikipedia.org/wiki/VOIP
815417
Since this assignment came from your Communications Class, I would imagine that it should have something to do with Communication.  So why not do a project on the telephone from it's invention until today's cell phones.  Do some research on Alexander Graham Bell for lots of information.  If you have to create something to go along with your written information, you could always find instructions on the internet for creating your own telephone.  Such as attaching two tin cans with a very long piece of string so that 2 people can talk to each other by listening and talking into each can.\n"Take two tin cans with one end removed from each. Punch a whole in the center of the intact end of each can. With a long piece of string, thread the two cans so that their flat ends face each other. Tie knots in the ends of the string. Pull the string tight, so that it is stretched between the two cans. Talk into one can; have someone else listen at the other."\nHere's a website with some information on Alexander Graham Bell; http://www.privateline.com/TelephoneHistory/History1.htm\nHere's a website with some information on the first cell phone;\nhttp://inventors.about.com/cs/inventorsalphabet/a/martin_cooper.htm\nHope this helps answer your question.
575439
I assume you mean something like a doorbell (even larger bells, like fire alarms, work the same way in general).\n\nWhen the button is depressed, a low-voltage signaling circuit is closed and current flows to a transformer. The transformer then closes in response to the signal, completing a high-voltage circuit. The transformer's job is to create a high magnetic field. This field than acts upon a hammer, draing it away from the bell. When the hammer contacts an open contact, the control circuit is opened, the transformer goes off, the magnetic field goes off. The hammer has a spring on it which pulls it back. It hits the bell. Ding-dong.\n\nThat's the simple version. Here's the longer version:\nhttp://home.howstuffworks.com/doorbell.htm
861697
Hi there:\n\nThe cell phone keyboard with the typical ABC\nis, as one answerer stated, a clone of the Alexander Graham Bell    configuration put out by Bell Laboratories, many years ago.\nAs someone stated, this crude way of using the numbers to\nget " words" was a memonic aid, so that "ASH 277" would be easier to remember, than all numbers. Since there were only a few phones, by grouping 3 or 4 numbers into a word, meant you only had to remember the last few digits, so " ROCK " would be the first area code for 999 phone numbers, and you just had to remember the last three digits.\n ( more Bell Labs trivia - did you know that the # sign is an octothorpe? This is out of a 1967 RED BOOK handbook for Bell Linemen... since then the name has been lost, and no one knows what it is called anymore, not even computer reference guides....   -- and, Alexander Bell wanted a word to sign in on a phone call CLEARLY, and searched around the world for a sound that was easy to recognize - the best he could find was the call for fishermen in foggy weather, who yelled AH - Looo, which reverberated like a fog horn and helped to prevent two sailing ships from hitting each other - He modified it a bit and invented the word " hello ", which never existed in the English language until he had all his operators use it... )\n  \n As for the QWERTY layout of the keyboard, here is a previous answer that I gave... your question is asked repeatedly on the ANSWER forum...\n\n__________________________________\n\nEarly typewriters were mechanically crude and the swing arms that\nhad the letters on the end moved 6 inches or more from a circle around\nthe center of the page. If two arms reached the same strike slot,\nthey jammed together, often bending the thin swing arms.\n\nA group of Engineers was given a typewriter by Remmington in New York, to design a jam- proof machine. Instead, the Engineers looked at a data base of the most used and least used\nletters of the English alphabet.\nThey put the most used letters on the LEFT hand, since most people are right  handed, and the most used letters on the weakest, least used fingers - note that  the letter "A" is on the baby finger on the left hand. The baby finger on the left hand was designated the weakest, most difficult to use finger, while the letter A is always abound across almost all amounts of actual typing.\nThe ploy worked, and typists who were using the common keyboard of the day, with all the letters in alphabetical order, slowed to an absoute crawl.\nRepairs of jammed keys stopped immediately.\nDVORAK was designed to improve typing, and " reportedly " quadruples the words per minute.\nRAND in England designed a keyboard with two bowls shaped to\nfit the human hand natural swing movements, so that the typist\ndoes not "reach" for top row keys and left and right keys, but\nmoves only the fingers, and unlike the old typewriters, which had\nkeys that would have to be pressed down against huge springs,\nabout one to two INCHES, the RAND keyboard had touch-screen like keys, that have no visible movement at all. The words per minute reach 2000, easily, by anyone with a bit of practice.\nToday, on a typical computer, programmers and general public are considered " good " if they can do 30 or 60 words per minute.\nSecretaries start at 120 words per minute.\nMost of the computer people I know still use two fingers, including\nsome of the fastest and best programmers, following the GIGO rule.\n(( Computers use a stack of memory, which programmers fill and recall with numbers, using either FIFO or FILO, First In, First OUT, or First in, Last Out. All early calculators like the HP65 I use, with RPN ( Reverse Polish Notiation) use FILO ). GIGO is a parody of this terminology, with Garbage In = Garbage Out. ie. Typing in huge amounts of poorly written and poorly tested program code, is not as fast as typing in well written, well tested
623115
I believe in cell phones.\n\nI believe that if I receive a call from you it's not the phone that I'm talking to, but to a person that is not even inside the phone.\n\nI believe that when it runs out of battery, even in the middle of a conversation with you, that doesn't mean you've disappeared from the universe.\n\nI believe that every telephone was designed to receive a unique number through a unique frequency, and that such number and frequency are there even when the telephone is not in use.\n\nI believe that all cell phone signals are everywhere (within the range of the antenna)\n\nI believe these signals can be received by every single telephone in the area, and that it is even possible that any of those signals could interfere with any telephone conversation.\n\nI believe this because I can understand it.\n\nJust try to explain it to someone who hasn't heard a word about electricity.\n\nAnd try to convince them it's not something evil just because they don't understand it.
648006
Its said that cell phones.. When you're blabbing away on your cell phone, did you know that your voice is transmitted from the antenna as radio frequency radiation? In fact, your voice puts out about half as much radiation as a microwave. Too bad we can't cook up a meal simply by talking to it on our cell phone.\n\nIt shouldn't come as a surprise that with that much radiation flowing from your phone, there's a good chance it's going to soak into your brain and cause some kind of damage. Cell phone users are at risk for getting rare brain tumors. In fact, studies have found that the rare tumors happen on the same side of the head that people usually use to talk on their cell phones.\n\nMillions of people use their cell phone on a daily basis - America alone has about 123 million cell phone users. Are you one of them? If so, you are putting a high-powered transmitter against your head - about an inch away from your brain. So don't sound so shocked to hear that talking on your cell phone might cause some serious damage.
214904
normally they work with antennas, electromagnetic fields propagation and communications systems. It has to do a lot with electrical signals and electrical behavior of components in the high frequency spectrum (normally above 9MHz, but radio signals of a few KHz might also be of interest)
146268
In the telephone network, the pair of wires that connects your phone directly to the nearest box(switch) is called the Local-loop (coz' it's a dedicated pair of wires local to your phone). It's also called the Last-mile. \n\nWhen a telephone operator swtiches to WLL, it essentially means that he repalced your box(switch, and end-point your and many of your neighbours telephone wires) with a Wireless switch. So now your phone would communicate with the switch not using a wire but through air. Rest of the network (beyond the box) is the same.\n\nThis essentially means that you can roam about with your WLL phone within the aerial range of that switch(which now becomes an antenna).\n\nOn the contrary, when, in a Mobile network, you move out of the range of your present antenna, another antenna picks you up. This the reason why WLL is also called a Limited Mobility Mobile system.
56104
First, this is not a science question.  Reiki has absolutely no scientific basis.  The mere fact that you can do it over the phone and supposedly achieve the same results as in person should show you the degree of baloney this is about.
526990
It can be demagnetized by being placed into an electromagnetic field.  Old ringer phones would produce such a field when the bell rang but I don't think a cell phone will produce an electromagnetic field sufficient to demagnetize a motel room key.\n\nAn interesting side note:  If you have an eel skin billfold, it will, over time, demagnetize your credit cards, motel keys, etc.  I don't know why but it will.
930133
I'm afraid the question is a little loaded and misleading. All things "cause" radiation, since all matter "causes" some form of radiation, even if it's only the odd photon of light. \n\nI think the question you are trying ask concerns studies of the effects of cell phone radiation. All those I have seen are inconclusive. However, over many years I have found New Scientist to be an invaluable source of good information and rational argument - try their web site.
1098757
Usually, with a cell phone, the answering machine (voice mail) is a service provided by your carrier. It will work even when your phone is off, has no signal, or is busy.\nIf you want to replace that with a software solution, I suggest that you divert calls to a landline number, which is connected to a computer modem, and use an answering machine program. I don't know of any good free programs though.
1001609
Geography refers to everything Earthified so that would have to mean a non-geographical call must be a space-call. However, the real answer is that landlines are actually connected to the ground and they are fixed lines and stuff so that makes them geographical. A mobile call is non-geographical because the "line" is not fixed to a geographical place, it's like cyber-calling because there are no wires for the little worms to go through.
444351
It is pretty odd that a calculator and a touch-tone telephone have exactly opposite layouts for their keypads, which have many identical components. The reasons behind the differences are not known for certain, but a few theories exist.\n\nThe first theory deals with the telephone's circuitry and tone-recognition hardware. When the touch-tone telephone was being designed in the late 1950s, the calculator and adding-machine designers had already established a layout that had 7, 8 and 9 across the top row. Data-entry professionals, and others who used calculators fairly regularly, were quite adept at navigating these keypads. They could hit the numbers extremely quickly, which was great for data entry, but not so great for dialing a touch-tone phone. The tone-recognition technology could not operate effectively at the speeds at which these specialists could dial the numbers. The telephone designers figured that if they reversed the layout, the dialing speeds would decrease and the tone-recognition would be able to do its job more reliably. This theory has little proof to substantiate it, but it does make sense.\n\nA second theory refers to a study done by Bell Labs in 1960. This study involved testing several different telephone-keypad layouts to find out which was easiest to master. After testing several layouts, including one that used two rows with five numbers each and another that used a circular positioning, it was determined that the three-by-three matrix that had 1, 2 and 3 across the top was the easiest for people to use.\n\nAnother theory is based on the layout of a rotary telephone. On a rotary dial, 1 is at the top right and zero is on the bottom. When designing the new touch-tone keypad, putting the 1 on the top-right didn't make much sense, because Western writing is read from left to right. But putting 1 on the top-left, and the subsequent numbers to the right, did make sense. Using that formula, the resulting rows fell into place, with zero getting its own row at the bottom.\n\nAll of these theories attempt to explain why telephone and calculator keypads are exact opposites, yet no one theory can be pinpointed as the definitive reason. It is common practice today to use the telephone-keypad layout when designing new products that utilize a keypad, such as Automated Teller Machines.
82028
By using their broad band network to transfer analog voice signals. At the end, they use IP phones that hook into the ethernet ports using RJ-45 cables instead of the regular RJ-11 cable used by regular phones. More details on http://computer.howstuffworks.com/ip-telephony6.htm .
44801
Signals come to and leave your phone by means of a voltage level that is carried over copper twisted lines.  These levels used to be 90 volts, however most phones today don't require that much voltage for a ring.\n\nWhen you pick up the handset of your phone, you have "opened" a line out or in depending on whether you are answering or dialing out.  The dialing out part is you simply telling the "voltage" where to go next.\n\nModern phone systems still use the copper twisted pair method, but now those systems carry data as well for products like DSL.  The signals can also be carried via fiber optics.\n\nThe point at where the call is distributed or routed is called a switch, usually located at an exchange or a central office.\n\nFor more detailed explanations, click the link below.  It has all the information you could ever wish to know about landline and other telephone systems.