The magnet will be stressed in the magnetic field, and finally the small magnetic needle will be parallel to the magnetic field, and the magnetic field near the ground is roughly from the south pole to the north pole, so the small magnetic needle is also roughly along the north-south direction.
2. Screwdriver with magnetic head
The magnet can hold the screw, which is very convenient to use.
3. Ring:
When the circuit is closed, the electromagnet attracts the elastic piece to make the hammer move in the direction of the iron bell, and the hammer hits the iron bell to make a sound. At the same time, the circuit is disconnected, the electromagnet loses its magnetism, and the hammer is bounced back, thus closing the circuit. So repeatedly, the bell keeps ringing.
4, electromagnetic relay:
Electromagnetic relay is an automatic switch controlled by electromagnet. Using electromagnetic relay can control high voltage and strong current with low voltage and weak current, and realize long-distance operation.
Extended data:
Magnets are not invented by people, but natural magnetite. The ancient Greeks and China discovered that there was a naturally magnetized stone in nature, called a "magnet".
This kind of stone can magically pick up a small piece of iron and swing it at will and always point in the same direction.
Early navigators used this magnet as their earliest compass to tell directions at sea. China was the first to discover and use magnets, that is, making a compass with magnets is one of the four great inventions in China.
After thousands of years of development, artificial magnets appeared in18th century, but the process of making stronger magnetic materials was very slow, and Al-Ni-Co was not produced until the 1920s.
Subsequently, ferrite was manufactured in 1950s and [rare earth magnets [including NdFeB and SmCo]] was manufactured in 1970s.
At this point, magnetic technology has developed rapidly, and ferromagnetic materials have also made components more miniaturized.
References:
Baidu encyclopedia-magnet