1) Differentiating various communication devices
Past
- Various tribes in Africa used a sound wooden drum to send
a message
- The Americans native people used smoke to send the message
that can be seen in several miles away
- Before the invention of electronics devices such as
telephone, the sending of message
to the long distance became a simple process
to the long distance became a simple process
- In the 18th century, the wooden barriers on the high pole in
french along the country sending a signal up to hundreds of kilometres away
Modern/Nowadays
-Claude chappe invented
a semaphore system in 1797 and now it still being used by navy to send a
message among the ship
- in 1838, an american named Samuel Morse inveted a code in
the form of long and short flases of the electric current or lamp.
-laptop
-radio
-telephone
-cellphone
-computer
