The first phones did just this, using an iron wire just like a telegraph would use. This created a lot of static, however, since everyone was using the earth to ground their phones. This was soon fixed when Bell invented a two-wire, or metallic, circuit in This meant that your phone conversation would require two wires, one to your friend and the other back, creating a complete circuit and thus not needing to be grounded in the earth, and also giving you a clearer conversation.
This meant, of course, replacing all the existing telephone wires with two-wire systems, but it was done by about , and all new lines were two-wire lines. At the same time, manufacturers were looking for ways to reduce static and line noise through the material used to conduct the electricity for phone conversations.
Then, in Thomas Doolittle of Connecticut developed the process for hard drawn copper wire, which increased its tensile strength and made it strong enough for overhead wires. The wires were insulated with cotton, cotton impregnated with paraffin, gutta percha or a rubber compound and much later—in the s—with PVC.
The twisting provides some protection against picking up interference from other wires nearby, and from interference generally. OK, so now we know all about converting our voices into electrical current, and how that current then moves down a wire and eventually gets reconverted into sound, which our friend hears and becomes the stuff of which conversations are born. But how does the current from our voice know to get to our friend?
But what if we want to be connected to several of our friends? Then everyone can hear the conversation—all they have to do is pick up their phone. This was really the case more-or-less for a lot of communities during the course of telephone history, and was known as a party line.
Great, if you want a mass phone call, like a giant joke email sent to all your friends. Not so good if you have to tell someone something private, like, say, if you work for a secret organization. In July a druggist in Hartford, Connecticut, wanted to be able to connect with several different doctors around town, and so he installed the first switchboard in his office. Soon this became a feature of all phone company central offices. A switchboard, in very basic terms, acts as the hub of all telephone activity.
An operator would sit at the switchboard and use small pieces of wire to connect that is, complete the circuit between yourself and, say, friend number one. You would literally call the operator for any call you wanted to make. An undertaker by the name of Almon Strowger in Kansas City, Missouri, had this same concern—or, rather, a similar one. He felt that the operators were connecting his potential clients with his competitors in an attempt to drive him out of business, so he with help from various technicians invented a device using electromagnets and hat pins in that made the connection between two parties without help from a human operator.
These flaws were soon fixed, however, and soon a dial replaced the keys see more about the dials themselves a little further down this page. Hi, Shatayah! We encourage you to submit your question to the Wonder Bank and keep researching at your library and online! Hello, boby! We are glad you liked this video. Welcome back, nneka! Wonder When Is Technology Old?
Welcome, nneka! What is the more interesting fact you learn? We would love to find out! Doodle jump is a game where you are a little doodle and you jump on platforms until you either fall or loose your lives, also I haven't played doodle jump in a long time.
Thanks for explaining the game to us, Not a Robot! Hello, Andrew! We think phones are cool, too. You can do a lot of different activities on cell phones today. Hi, Sally! Is red your favorite color? Hi, DeRpY-Chan!
We are sorry you have not seen our responses, but we have been responding to your comments. Hello, Landin S! Hi, alexys! We are undergoing some spring clearing site maintenance and need to temporarily disable the commenting feature.
Thanks for your patience. Drag a word to its definition. You have answered 0 of 3 questions correctly and your score is:. Want to add a little wonder to your website? Help spread the wonder of families learning together. We sent you SMS, for complete subscription please reply. Follow Twitter Instagram Facebook. How does a phone work? What's the difference between a cell phone and a land line? Who patented the first telephone? Tags: See All Tags Alexander Graham Bell , cable , cell , cellular , communication , data , digital , ear , frequency , home , inventions , land , line , microphone , patent , phone , radio , ring , science , smartphone , sound , speaker , switch , technology , telephone , tower , transmit , voice , wave , wire.
Wonder What's Next? Wake up, sleepy head! Try It Out We hope you enjoyed learning all about how phones work today in Wonderopolis! Learn even more when you check out the following activities with a friend or family member: Want to learn more about the phone right now?
What are you waiting for? Make a call! Reach out and touch someone…with your voice! Use a phone to call someone you haven't spoken to in a while. Catch up with them and let them know you care. You could even share with them some of the things you learned from today's Wonder of the Day! Sit down and have a discussion about phones with an adult friend or family member.
You might be surprised to learn about how many different types of phones they've used over the years. Do they remember ever using an old rotary dial phone? Do they have any pictures of old phones they used to own?
If not, jump online and look up pictures of old phones. Which ones do they remember using? How do they compare to today's phones? Have fun on your trip down memory lane! Ready for a field trip! Ask an adult friend or family member to take you on a field trip to a local electronics store.
Ask a salesperson to show you the range of phones available for sale. Do they still sell corded or cordless land line phones? How do those phones compare to the latest and greatest smartphones available? Request a demonstration of the newest smartphone features. Talk with the salesperson about what changes they expect to see in phones in the future.
Will they get bigger or smaller? What new features might they have? What features would you like to see in the next mobile phone? Did you get it? Once the receiving party picked up, the operator would connect the two people together in exactly the same way the simple intercom is connected! It is that simple! In a modern phone system, the operator has been replaced by an electronic switch.
When you pick up the phone, the switch senses the completion of your loop and it plays a dial tone sound so you know that the switch and your phone are working. For more information on tones, see How Guitars Work. The dial tone sound is simply a combination of hertz tone and a hertz tone, and it sounds like this. Click here to hear a dial tone. You then dial the number using a touch-tone keypad.
The different dialing sounds are made of pairs of tones:. Click here to listen to a touch-tone number. If the number is busy, you hear a busy signal that is made up of a hertz and a hertz tone, with a cycle of one-half second on and one-half second off, like this:. Click here to listen a busy signal. In order to allow more long-distance calls to be transmitted, the frequencies transmitted are limited to a bandwidth of about 3, hertz.
All of the frequencies in your voice below hertz and above 3, hertz are eliminated. That's why someone's voice on a phone has a distinctive sound. Compare these two voices:. Call up someone you know and play the 1,hertz sound file on your computer. The person will be able to hear the tone clearly. The person will also be able to hear the 2, and 3,hertz tones. However, the person will have trouble hearing the 4,hertz tone, and will not hear the 5, or 6,hertz tones at all!
That's because the phone company clips them off completely. For lots more information on telephones, telephone networks and related technologies, check out the links below. Sign up for our Newsletter! Mobile Newsletter banner close. Mobile Newsletter chat close. Mobile Newsletter chat dots. Mobile Newsletter chat avatar. Mobile Newsletter chat subscribe. Telephone Technology. How Telephones Work.
Telephone Design " ". A switch to connect and disconnect the phone from the network - This switch is generally called the hook switch. It connects when you lift the handset. A speaker - This is generally a little cent, 8-ohm speaker of some sort. A microphone - In the past, telephone microphones have been as simple as carbon granules compressed between two thin metal plates.
Sound waves from your voice compress and decompress the granules, changing the resistance of the granules and modulating the current flowing through the microphone. Telephones: Wires and Cables " ".
Telephone wires and cables connect your home phone to a huge communications web. Digital Phone Calls The concentrator digitizes your voice at a sample rate of 8, samples per second and 8-bit resolution see How Analog and Digital Recording Works for information on digitizing sounds.
Hand Generated! Creating Your Own Telephone Network " ".
0コメント