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Beam current refers to the portion of the gun current in a cathode-ray tube (CRT) that successfully passes through the aperture in the anode and impinges on the fluorescent screen.
Key Points:
- Gun Current: This is the total current emitted by the electron gun in the CRT, which includes all electrons emitted from the cathode.
- Aperture in the Anode: The anode has an aperture or opening that allows some of the electrons emitted by the cathode to pass through. The anode helps accelerate and focus the electrons into a narrow beam.
- Fluorescent Screen: The beam current that passes through the anode aperture eventually hits the fluorescent screen, causing it to emit light and create the visible image on the CRT display.
- Importance: The beam current is crucial for the operation of the CRT, as it determines the brightness and intensity of the image on the screen. Higher beam current generally results in a brighter image.
In summary, beam current is the useful portion of the electron flow in a CRT that contributes directly to image formation by reaching the fluorescent screen.
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