Do You Know
Questions & Answers on General Knowledge.
How does a video recorder work?
A video recorder is much like a normal tape recorder, except that it records far more information each second. When you play an audiotape in a normal tape recorder, small magnetized regions of tape move past a playback head. This playback head consists of an iron ring with a narrow gap in it and there is a coil of wire wrapped around the ring. As the magnetized regions of the tape pass near the ring's gap, they magnetize the ring. The ring's magnetization changes as the tape moves and these changing magnetizations cause currents to flow in the coil of wire. These currents are amplified and used to reproduce sound. When you record the tape, the recorder sends currents through the wire coil, magnetizing the iron ring and causing it to magnetize the region of tape that's near the gap in the ring. In a video recorder, the tape moves too slowly to produce the millions of the magnetization changes needed each second to represent a video signal. So instead of moving the tape past the playback head, the video recorder moves the playback head past the tape. As the tape travels slowly through the recorder, the playback head spins past it on a smooth cylindrical support. The tape is wrapped part way around this support and two or more playback heads take turns detecting the patches of magnetization on the tape's surface. The tape is tilted slightly with respect to the spinning heads so that the heads sweep both along the tape and across its width. That way, the entire surface of the tape is used to record the immense amount of information needed to reproduce images on a television screen. During recording, currents are sent through the heads so that they magnetize the tape rather than reading its magnetization.
Why is a car's rear window put and kept under stress, and what has this to do with polarization?
Exactly what is light? Is it a wave or particles?
Which is the largest galaxy?
Can you get a suntan or sunburn through glass?
How efficient are solar energy cells and windmills in producing energy for everyday use?
When do I send greenhouse gases in the air, and how can I make a difference?
Is there an inexpensive device for detecting leaks from a microwave oven?
Why isn’t it over ’til the fat lady sings?
Why are vain people said to be “looking for the limelight”?
Why is a surplus of anything called a “backlog”?
How does water divining work?
How does the television camera record the picture?
What is the surface of Mercury like?
Why is natural ability called “talent”?
Is Earth at the center of the universe?
What is the Arctic?
Why does copper conduct electric currents better than steel and lead? Why do copper and aluminum seem to conduct about the same?
How does a boomerang work?
Why do you think you see water on a road ahead of you when it's not really there?
How are luminol and fireflies related?
What path does sunlight follow for you to see a mirage?
How are light and sound the same? How are they different?
How were the planets formed?
What were high-wheelers?
Why are so many flowers brightly colored?
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