electronics?

Question

an electron tube containin three electrodesi is known as triode.in vacuum diode consists of two electrodes namely cathode and anode or plate. we have cloud of negatively charged electrons near the cathode called space charge. in triode i have extra electrode named grid and this grid eliminates space charge around cathode. how it happens? because grid is given negative voltage known as bias . if this bias is negative how the grid removes space charge which is also negative charge.

my question is how triode removes the space charge?
if it is by bias how it happen beause both bias and space charge is negative?
folks please help

Answer 1

Did u hear the term 'Thermoionic emission'?
When a metal piece is kept in a vacuum and is heated to incandescence, the electrons escape away from the surface atoms and surround the metal object in a cloud of free electrons. This is called thermionic emission or Edison effect.This was discovered by Thomas Alva Edison.It was the basic of the electric bulb and diodes,triodes etc.
In a common thermoionic tube cathode & anode are enclosed within an evacuated bulb and leads to the respective electrodes are brought out through the base of the bulb.Cathode is a hollow cylinder (usually) and is heated by a fine resistance wire within it.Electrons escape from cathode forming space charge and are attracted to the plate or anode. If the potential diff (pd) is small only a few escaped electrons reach the plate. Majority of electrons penetrate a small distance to the cloud of space charge and return to cathode.As plate potential increase more and more electrons are drawn to it.When further increase of pd doesn't increase plate current then this state is called saturated.BTW minimum energy required to escape electrons is called work potential.Now, in a diode emission occurs at cathode only so its flow is in a single direction, from cathode to anode.Usually circuit application of diode use this one-directional flow.eg. rectifier to convert a.c to d.c.
Problem comes with the introduction of grid.Tht was some scientist called Lee(Sorry, I forgot the whole name) who innovated the electron flow by inserting a third electrode called grid between cathode and anode.It is usually open either screen or coil of naked wire. When grid is negative the resulting field increase the space charge near the cathode and decrease the electron flow through the grid to the plate. As grid is nearer to anode the current flow is effected by change in grid voltage and not anode voltage (plate voltage) like the earlier case of diode."A relatively small variation in voltage on the grid causes a large variation in anode current"(Yeah!This is a quotation of my Physics teacher).The saturation of space charge is reduced by repulsion effect. It can thus function as amplifier and called triode.This is very useful in signal processing.Mobile phone is an example using amplifier for speaker, radio transmission and signal processing.

Answer 2

Sorry, i don't be attentive to the place you ought to purchase "low value" issues. you may might desire to stipulate "low value". a splash hint: a hundred yen is below an American dollar. whilst you're in Tokyo, circulate to Asakusa. it is an particularly exciting, tourist place. there are a number of cool Buddhist temples to confirm. There are additionally streets crammed with small keepsake shops. some souvenirs are costly, yet many are particularly low value. (a splash hint on souvenirs, no count if it is purely too costly, likelihood is it is greater least costly at yet another shop on the line.) immediately I purely have been given back from exploring areas of Tokyo. I explored places utilising the Yamanote JR line. there are a number of exciting issues to do utilising this line. close to the Shinagawa station, there is the widespread Sengakuji temple. on the Harajuku station, there is the widespread Meiji Shrine. There are additionally 2 artwork museums on the element of the shrine. additionally circulate to the Tokyo Tower, placed close to the Hamamatsucho station. it is a few distance cool tower. properly, those are basically some issues to do in Tokyo. i'm hoping it facilitates.

Answer 3

The charge is nullified due to repulsion