Presentation on theme: "In 1876 Alexander Graham Bell invented the telephone with the help of his assistant Thomas A. Watson Telephone is the Greek word for sound Mr. Bell got."— Presentation transcript:
In 1876 Alexander Graham Bell invented the telephone with the help of his assistant Thomas A. Watson Telephone is the Greek word for sound Mr. Bell got the idea for the telephone from a German inventor Hermann von Helmholz Mr. Bell invented the telephone by accident when he was trying to invent a device that could send more than one telegram at a the same time. The first telephone didnt have a bell, so the caller had to tap the phone with a hammer to let the receiver know a call was being sent to them. Thomas Watson invented the bell for the telephone.
The first telephone operator only answered the phone when they felt like it. The operator would pick up the phone and say number please. If the number wasnt busy the operator took a chord and plugged it into a switchboard that connects the caller to the number. The operator system changed because there were to many people with telephones and it cost to much money to have that many operators working.
A modern telephone transmitter which is essentially a carbon microphone contains loosely packed carbon grains. When someone speaks into the telephone the diaphragm vibrates causing the carbon grains to be compressed and released. This motion varies the current flow in the associated electric circuit. When transmitted to a distant identical instrument causes the diaphragm in it to vibrate in response to the fluctuations induced by the nearby field.
The first simple telephone were comprised of a long string and two cans were known to be in the 18 th century. A electrical voice transmission system was first demonstrated by Johann Philipp Reis in His machine consisted of a vibrating membrane that opened or closed an electric circuit.
The telephone is used for communicate with friends and family The telephone is a way to express your self The telephone is a way to get information The telephone is used for home or to take with you anywhere
The telephone can tell the time and date The telephone can tell if you have a missed call or a incoming call The telephone can tell what time people called The telephone can tell how loud it is how much light it has and how much battery is left
The 1 st automatic telephone was made in 1891 in Kansas city. In 1921 the Detroit police department began experimenting with one-way vehicular telephones. In 1948 wireless telephone service was available in almost 100 cities and highway corridors. In 1970 picture phone service debuted in downtown Pittsburgh Pennsylvania. In 1973 martin Cooper of Motorola made the 1 st cell phone call to his rival at AT&T.
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