History editor
Compass, also known as compass, is a guiding instrument invented in ancient China by using the polarity of magnetic fingers. Therefore, the introduction of Sina must start with magnets.
Magnets are often called "magnets", which attract many iron filings tightly, just like a kind mother attracts her children, so people call them "magnets".
Magnets attract iron because the magnetic poles at both ends of each magnet are different, one is called positive pole and the other is called negative pole. The earth where human beings live is also a huge natural magnet. The north pole and south pole of the earth also have different magnetic poles. The north pole of the earth is negative, and the south pole of the earth is positive. According to the principle that like magnetic poles repel and opposite magnetic poles attract, take a magnetic needle that can rotate freely. No matter where you stand on the earth, its positive pole always points to the north, and its negative pole always guides you.
manufacturing method
Materials: sewing needle, candle, iron wire, cold water, transparent plastic bottle, hammer, fine wooden stick.
Production method:
1. Wrap the sewing needle with iron wire, then put it in the fire to burn it red, and then immediately immerse it in cold water to cool it. Remember: when dipping, the needle must be placed in the north-south direction, so that the needle can become a small magnetic needle. Also, be careful not to burn!
2. Cut the bottle mouth of the plastic bottle, punch a hole in the center of the bottom with a hammer, then tie one end of the thin thread in the middle of the small magnetic needle, and then pass the thread through the hole. Turn the plastic bottle upside down and let the small magnetic needle rest slowly. At this time, you will find that one end of the small magnetic needle points to the south and the other end points to the north.