Understanding Cathode Ray Tubes: Exploring Electron Movement

[Physicsissuef]

Can somebody please explain what actually happens in cathode ray tube? Is there any current passing through the tube? How does the anode (positive electrode) lost electrons? Is it before the effect of cathode rays? How does the cathode (negative electrode) have bigger amount of electrons? Is it before the whole process?

 

[klystronman]

i am not the smartest one but ...

i am not the smartest one but basically a tube operates on voltages and the the attraction of opposites and under vacuum. So the cathode (electron emmiter) is heated so the electrons are boiled off and flow towards the anode. the current is controlled by varrying the voltage from anode to cathode and sometimes the cathode temperature. more advanced tubes have plates in the electron path that replicate this process. so basically a tube operates on controlling a current by the use of voltage differentials.

a good example would be an amplifier tube. cathode emits electrons. current controlled by voltage on anode ring between cathode and anode. then a microphone is attached to the anode ring voltage supply so that the voltage varies when noise is applied. the small voltage from the microphone causes a corresponding waveform in the current flow. by attaching a resistor to the current thru a tube you have and amplified voltage across it coresponding to the voltage from the microphone.

check out older tube amplifier circuits

good luck

 

[klystronman]

oops...cathode ray tube

oops...cathode ray tube
okay
electrons emitted from cathode toward screen at say 20000 volts (could be different) beside the path by the cathode are electrically charged plates that are varried to dirrect the path of electrons to phosphors on the screen that glow when struck.. the electrons then fall back to the cone of the tube to complete the circuit.

now if you set rules for a wave form on a pulse. then you know that the pulse length is for the time it takes to scan every pixel on the tube. during that scan you have a pattern like reading a paper left to right / top to botton. so now you have a pulse with all the data to fill a matrix ( tv screen) and it repeats itself at a given interval to keep the phosphors bright.

hope this helps