The cathode-ray oscilloscope (C.R.O.) consists of the following components:
- The electron gun.
- The deflecting plates.
- A fluorescent screen.
The electron gun
| Parts of Electron Gun | Function |
|---|
| Filament | To heat the cathode. |
| Cathode | Release electrons when heated by filament. |
| Grid | - The grid is connected to a negative potential. The more negative this potential, the more electrons will be repelled from the grid and fewer electrons will reach the anode and the screen.
- The number of electrons reaching the screen determines the brightness of the light. Hence, the negative potential of the grid can be used as a brightness control.
|
| Focusing Anode and | - The other feature in the electron gun is the use of the anode.
- The anode at positive potential accelerates the electrons and the electrons are focused into a fine beam as they pass through the anode.
|
| Accelerating anode | |
The deflecting plates
| Part of the deflecting system | Function |
|---|
| Y-plate | The Y-plates will cause deflection in the vertical direction when a voltage is applied across them. |
| X-plate | On the other hand, the X-plates will cause the electron beam to be deflected in the horizontal direction if a voltage is applied across them. |
The fluorescent screen
- The screen is coated with a fluorescent salt, for example, zinc sulphide.
- When the electrons hit the screen, it will cause the salt to produce a flash of light and hence a bright spot on the screen.
