Communication is the the transmission and reception of meaningful information.Through various technological devices such as the telephone,telegraph, radio, television,radar,radio telescope, orbiting satellites, microwave relays and lasers as well as the advances made in the field of electronics human communication is the beneficiary of immeasurable favors.Fundamental to these modes of communication is the conversion of light and sound to electrical energy , and the use of electromagnetic waves for the transmission and reception of information.
Contributors to the development of telephone
Alexander Graham Bell
He is the acknowledge inventor of the telephone.
he is given the credit as the inventor of the telephone. The first telephone model was made by his assistant ,
Thomas Watson.
Hans Cristian Oersted
He discovered the electromagnetism.
On 21 April 1820, while preparing for an evening lecture, Oersted noticed a compass needle deflected from magnetic north when electric current from a battery was switched on and off. This deflection convinced him that magnetic fields radiate from all sides of a wire carrying an electric current, as do light and heat, confirming a direct relationship between electricity and magnetism. Three months later he began more intensive investigations and soon thereafter published his findings, showing that an electric current produces a magnetic field as it flows through a wire.
Michael Faraday
He is the acknowledge father of modern electricity.His discovery is the reverse of Oersted's. While Oersted's experiment demonstrated that current carrying conductors produce a magnetic field produces or induces current. He demonstrated that a changing current in a coil induces current in a nearby coil even if the coils are not physically connected. This is called the principle of electromagnetic induction.
with this principle Faraday built the worlds first electric generator.
Joseph Henry
He work on the same experiments on electrical induction as Michael Faraday But he did not publish them first. He showed that electromagnetism can be used to communicate with. In a class Demonstration that he performed he showed how an electromagnet with current can attracted an iron bar which in turn struck a nearby bell. This was considered a case of electrical signaling.
James Clerk Maxwell, Heinrich hertz and Guglielmo Marconi
Maxwell put together he principles of Oersted, Faraday, and others and predicted the existence of electromagnetic waves. Twenty years later Hertz experimentally showed the existence of such waves which he called radio waves. Marconi use radio waves to send messages without wires.
Thomas Edison
He devised the carbon transmitter,it works on the principle that the electrical resistance of carbon changes with acoustic pressure exerted on it.
Lee De Forest
He built a vacuum tube, the triode which made possible the building of a nationwide telephone system. On January 25,1915, the first transcontinental telephone system line using three vacuum tube reapeters opend between New York city and San Fransisco-The worlds longest telephone line .This invention ushered in te electronic age for telephone.
"The telegraph uses a special code ,the Morse code in transmitting messages. The Morse code assigns unique pattern for each character of the alphabet, as well as to the ten numerals and punctuations"
