From: pauld@exploratorium.edu
Date: Thu Dec 05 2002 - 22:41:09 PST
Message-Id: <200212060641.gB66f8j28756@isaac.exploratorium.edu> From: pauld@exploratorium.edu Subject: Re: pinhole Television Date: Thu, 5 Dec 2002 22:41:08 US/Pacific
All the even numbered lines are drawn in 1/60 of a second, then all the odd #
lines in the next 1/60 of a second. The persistence of vision of the human eye
shows a blinking image at 60 cycles as a continuous image.
The electron beam is pushed across the screen to make circa 250 lines in 1/60
second. Or about 15000 lines per second.
The beams can be moved across the lines so fast because electrons are low in mass
and so easy to accelerate.
Paul D
> One of my students asked how it is possible for a television set (CRT) to
> move the electron beam at such a high rate and with such accuracy that we do
> not begin to perceive the "lines" that are being "drawn". Anyone got a good
> answer for the lad?
>
> Charlie Bissell
> Hillsdale High School
>
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