Cathode Ray Tube(CRT) , Definition , Parts of CRT

                   -: Cathode Ray Tube :- 

CRT is the heart of CRO which make the applied signal visible by the deflection of a beam of electron.CRT essentially consist of an electron gun for producing a stream of electron focusing and accelerating anode for producing a narrow and sharply focused electron beam,horizontal and vertical deflection plates for control the beam path as shown in figure.

Image source : Google

CRT has mainly the following parts - 
(a)- Electron gun assembly
(b)- Control Grid 
(c)-Focusing anode
(d)-Deflection plate assembly
(e)- Fluorescent screen 

(a)-Electron gun assembly :- 

                                                                 Electron gun assembly consists of an indirectly heated cathode that control grid held at negative potential with respect to cathode while as the to anode are maintained at high positive potential with respect to cathode.
(b)-Control Grid :- 

                                                  Control grid in the CRT is cylindrical with a small opportunity in line with the cathode. The electron emitted from the cathode emerge from the negative bias voltage applied to the great controls the beam current the the essentially for bright name of spot depends on the beam.

(c)-Focusing anode:- 

                                                       The beam of electron converged and focus on the screen by two anode which from the electrons the first anode is kept highly positive with respect to the cathode.

The second and is still operated at high positive potential and does most of the acceleration of the beam and increasing in velocity this process is called Accelerating anode.

(d)-Deflection plate assembly :-

                                                                          The deflection system consists of a pair of horizontal and vertical deflection plate.

1-when the plate are at zero voltage the beam mid-day off screen.

2-when horizontal mode positive with respect to cathode and all other plates are zero voltage it accelerates the beam and all spot moves horizontally to the right.
3-similarly when vertical mode is positive the spot moves vertically upward

(e)- Fluorescent Screen :- 
                                            There is a screen at the other end of tube which is coated with a fluorescent material such as Zinc Sulphide .