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Question
Explain construction and working of cathode ray tube.
Solution
A cathode ray tube is a specially designed vacuum tube in which an electron beam controlled by electric or magnetic fields are used to visual display of input electrical signal on the screen which is coated with fluorescent materials.
A CRT is a complex arrangement it is described by various parts like,
a) Electron gun
b) Deflective system
c) Fluorescent screen
d) Glass envelop
Electron gun:
1. The focused and accelerated electron beam is given out by the electron gun.
2. It consist of heater, a cathode, a grid, a pre-accelerating anode, a focussing anode and an accelerating anode.
Deflection system:
1. On reflecting particle “Pre requisites” and points 6,7 and 8 over there we get a general picture of electrostatic deflection.
2. There are two pairs of strictly parallel metal plates, two of them are parallel to X-axis called y plates as the causes deflection along X-axis.
3. The deflected beam generates as bright spot on the screen.
` Y=D/2 xx l/d xx V/(VA) `
Fluorescent screen: The interior surface of circular front face of the CRT is coated with a thin translucent layer of phosphors.
