Vacuum tubes were invented in 1904 by John Ambrose Fleming and were a basic component for electronics throughout the 20th century, enabling technologies like radio, television, radar, and computers. Vacuum tubes work by emitting electrons from a heated cathode through a vacuum and rely on the thermionic and photoelectric effects. Early vacuum tubes included diodes, which could rectify AC, and triodes, which were invented in 1907 by Lee de Forest and added a grid electrode to control current flow. While largely replaced by transistors, vacuum tubes are still used for high-power radio applications due to their efficiency and cost effectiveness.

1. Name: Ahmed Khaled
ID: 14105269

2. Vacuum Tubes

4.  invented in 1904 by John Ambrose
Fleming
 vacuum tubes were a basic component for
electronics throughout the 20th century
 diffusion of radio, television, radar, sound
recording and digital computers.

5. How Vacuum tubes works :
 Vacuum tubes mostly rely
on a cathode heated by the
filament is called a thermionic
tube or thermionic valve.
 electron emission through
the photoelectric effect.

6. Diodes :
 invented by John Ambrose Fleming
 could be used as a rectifier of AC
and as a radio wave detector

7. Triodes :
 The only one who succeeded was
inventor Lee de Forest in 1907.
 By placing an additional
electrode between cathode
and anode.
 the grid was changing the
current flowing from the cathode
to the Anode

8. 
 Used in big radio stations, especially for power
levels above 10,000 watts and for frequencies
above 50 MHz. High-power TV stations and
large FM stations are almost exclusively
powered by tubes. The reason is cost and
efficiency

9. Vacuum tube devices :
 Cathode ray tubes •Vacuum fluorescent display

10. Vacuum tubes using field electron
emitters
 design uses a cold cathode in
the form of a large-area field
electron source( field emitter
array).
 include much and the ability to
provide high power output at
low power consumption

11.  we may find application in :
 microwave devices including mobile phones for :
 Bluetooth
 Wi-Fi
 in radar and for satellite communication

12. Gas-Filled Tube :
 and operate by ionizing the gas
with an applied voltage
 Ionizing is dependent on the
pressure of the fill gas and
geometry of the tube

13. •Nobel Gases :
 Helium :is used in helium–neon lasers
 Neon : Used in fluorescent tubes with high power
and short length, e.g. industrial lighting tubes

14. References :
 http://www.vacuumtubes.net/How_Vacuum_Tubes
_Work.htm
 http://www.answers.com/Q/What_is_the_uses_of
_triode_transistor