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What is color television?
The human eye sees an object and can see its colors because the light it emits, or light from its surface, bounces off, enters...
What is an audio CD?
Edison's phonograph underwent constant innovation to become a popular electric phonograph. It is made up of the motor, the turntable, the receiver, and the...
What is the principle of the fire detector?
Fire harms human lives and property, damages the ecological environment. Fire prevention is a matter of concern to all humans. If it is possible...
What is the principle of the theft alarm?
In important places such as money, gold, silver, underground record storage, etc., if a fraudster suddenly sneaks in. the burglar alarm will immediately sound...