Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Ron Hughes on 03/05/2010 15:56:31
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Say we had a CRT that is 5 meters long, what would the dot on the phosphor look like?
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To answer your headline question not very much if the design is correct. Remember this is essentially the way electron microscopes work.
The question in the question cannot be answered without more information being specified and this information is of a highly technical nature relating to the size of the electron source the electron optics the intensity of the beam and the accelerating fields. Again if correctly designed the spot can be made very small
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Lets take an old o scope crt. It was probably 10 to 12 inches long. Stretch the neck out so that the total length is say 3 meters. Do I still get the same size dot?
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Lets take an old o scope crt. It was probably 10 to 12 inches long. Stretch the neck out so that the total length is say 3 meters. Do I still get the same size dot?
I suspect you would not be able to focus the beam without making some changes to the drive electronics.
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Lets take an old o scope crt. It was probably 10 to 12 inches long. Stretch the neck out so that the total length is say 3 meters. Do I still get the same size dot?
If you're just stretching the neck of the tube then I don't think there'd be much difference because the focusing and deflection plates/coils are usually located at the throat of the neck, so the distance between the focusing and deflection plates/coils and the phosphor screen will be about the same. If you scale the entire tube up though, then you'll be increasing this distance so I'd expect that you'd either need better focusing and deflection to maintain the same dot size/sharpness or settle for a larger, more blurry and dimmer dot.