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Alexander Graham Bell

Alexander Graham Bell. And his Invention of the Telephone. By Hannah Jennings. Alexander Bell. Born on March 3rd, 1847 in Scotland Educated the deaf 1878 invented the telephone 1878 founded the Bell telephone company. Alexander Bell.

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Alexander Graham Bell

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  1. Alexander Graham Bell And his Invention of the Telephone By Hannah Jennings

  2. Alexander Bell • Born on March 3rd, 1847 in Scotland • Educated the deaf • 1878 invented the telephone • 1878 founded theBell telephone company

  3. Alexander Bell • Volunteered for the deaf for many years • Earned the Volta Prize for his invention • Established the Alexander Graham Bell Association for the deaf • Died on August 2nd, 1922

  4. The Telephone 4). 2). Four Main Parts: 1). Dialing Mechanism 2). Transmitter 3). Ringer (inside) 4). Receiver 1). 3).

  5. Dialing Mechanism • On the handset, or base of phone • Has set of buttons or keys called a key pad • Older telephones had rotating keypad called rotary dial • The computer recognizes the tone each key produces, and dials it

  6. Dialing Mechanism

  7. Sending Signals • The speaker’s voice travels through an electric current • The current goes from the transmitter to the hook switch • Then from there, it goes to the wall jack • The wall jack sends the signal into the telephone network

  8. Sending Signals To Wall Jack

  9. Transmitter • Modern phones use a foil-electret condenser transmitter (a type of microphone)

  10. Transmitter Backplate Diaphragm • The circular diaphragm is stretched over a hollow back plate

  11. Transmitter Diaphragm • The diaphragm touches the back plate only in some places

  12. Transmitter Electric Field • When the diaphragm vibrates, it condenses the air, and that influences the electric field

  13. Transmitter To Telephone Network • When the electric field changes, it changes the electric current that is sent into the network

  14. Transmitter • Variations in current “copy” the speaker’s voice, and send the current through a wire

  15. Ringer • Signals incoming calls • Early Phones had small bells • Modern phones are replaced with a computer chip that makes a sound

  16. Receiver • Converts electric current into sound through a speaker

  17. Receiver Magnet Wire Coil • When pulses of electric current come through the wire coil, a magnetic force is created, which moves the magnet

  18. Receiver Diaphragm • The magnet vibrates the diaphragm, which creates sound waves to duplicate the speaker’s voice

  19. Receiver Diaphragm Magnet Wire Coil Speaker

  20. Telephone Networks • Signal leaves the house and goes to a telephone box

  21. Telephone Networks • From the box to the telephone pole, and from the pole to the local exchange

  22. Telephone Networks • An exchange is a building that is connected to all the telephone poles in the area. It connects the incoming call with the number that was dialed

  23. Telephone Networks • From the local exchange, to the main exchange, from there to the international exchange • The main and international exchanges serve the same purpose as local, except they are connected to the smaller exchange buildings • It then goes in the backwardsorder to the other telephone

  24. Telephone Networks Telephone Poles Telephone Boxes Local Main

  25. Cell Phones • Mobile devices that transmit and receive radio signals • Communicates through an antenna transmitter • Transmitter serves a single geographic area called a cell

  26. Cell Phones • The cell connects with a regular telephone network • It has the same basic parts of a telephone

  27. Telephones in Remote Areas • Too expensive to run wires to low populated areas • BETRS fills in the “gap” (Basic Exchange Telephone Radio Service) • Each house has a transmitter that sends radio signals to the telephone exchange

  28. BETRS Telephone Exchange Telephone Transmitter Radio Signals

  29. About the Author I am Hannah Jennings. I did the telephone because I like to talk on it. I am 12 years old, and in the 7th grade. I live in Winston- Salem, North Carolina.

  30. Bibliography • “Alexander Graham Bell- Biography.” What you need to know ABOUT. June, 2003. 4/26/2004. Http://inventors.about.com/library/inventors/ bltelephone2.htm. • Brian, Marshall. “How Telephones Work.” How Stuff Works. 4/29/2004. Http://electronics.howstuffworks.com/ telephone.htm

  31. Bibliography • Brodsky, Arthur. “Telephone.” The World Book Encyclopedia.(volume 19). 2003. World Book Inc. April 27, 2004. • Hounshell, David, A. “ Bell, Alexander Graham.” The World Book Encyclopedia (volume 2). 1999. World Book Inc. April 27 ,2004.

  32. THE END

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