Vacuum Tube

Clear those pesky gas particles out of the way and negatively charged metal plate. and negatively charged electrons will leap straight for a positively charged metal plate.

in other world, an electrical  current  will flow more efficiently through a vacuum tube. It consists of a glass bulb emptied of air.On one side is a metal filament. on the other a metal plate.An electronic ,which are attracted to the metal plate.

Applying a current to a small grid placed between the filaments and the plate makes. it possible to not only transmit but also amplify electrical signals along their path. This  elaboration on the vacuum tube,known as a triode vacuum tube. revolutionized communication in early twentieth century enabling long-distance telephony radio,and TV.