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Computer - Charles Babbage
A computer receives data through an input unit based on the instructions it is given and after it processes the data, it sends it back through an output device. -
Telegraph - Joseph Henry
A telegraph sends information by making and breaking an electrical connection. -
Telephone - Alexander Graham Bell
The electrical energy travels over wires to another phone and is converted from electrical energy to sound waves again which can be heard by someone on the other end of the phone. -
Radio - Guglielmo Marconi
Radio works by transmitting and receiving electromagnetic waves. The radio signal is an electronic current moving back and forth very quickly. A transmitter radiates this field outward via an antenna; a receiver then picks up the field and translates it to the sounds heard through the radio. -
Television - John Logie Baird
A TV set turns the video signal into beams of tiny particles. It shoots these beams at the back of the screen through a picture tube. The beams do the pixels on the screen in a series of rows to form the picture. -
Tablet - Alan Kay
They have a screen, are powered by a rechargeable battery, often include a built-in camera, and can store all kinds of files. -
Mobile phone - Martin Cooper
A microchip in the phone modulates a radio wave using the electrical signal. The radio wave travels through the air to a nearby cell tower; the tower sends your voice to the person you are calling and the process is reversed so that the person on the other end can hear your voice.