Magnet has N poles (Arctic) and S poles (Antarctic). If you cut the magnets from the middle, you will find that the two magnets that are cut are still N and S poles. And then cut is still the case, no matter how small cut, N pole and S pole will always appear in pairs, can not take its pole, which is why?
N and S on the eternal "love"
On the N and S "love" we have to understand from the microscopic origin of solid magnetic. It turned out that the electrons in the material had spin magnetic moments - like a very tiny magnet, and electrons, like the planets, around the nucleus around the nucleus, produced a superposition of orbital magnetic moments, spin moments and orbital magnetic moments The total magnetic moment of the electrons is formed. A different arrangement of electrons can cause the magnetic properties of the atoms to be different.
When these magnetic atoms are arranged in the same direction, the magnetic properties appear on the whole of the material. If the magnetic moments of the material are messy, there will be no magneticness as a whole. Understand the magnetic source, N pole and S pole why there will be pairs, we are easier to understand. Since the magnetism of the magnet itself comes from the magnetism of the internal atoms of the magnet, and the atom itself is like a tiny magnet, and has N and S poles, it can also be said that the microscopic pole is paired, so no matter how cutting the magnet, it always There will be pairs of poles.
Magnetic on iron "soft spot"
Iron is a ferromagnetic material, the ferromagnetic material inside the ion and the magnetic moments of the existence of interaction, will make the regional magnetic moment in one direction, and then the formation of magnetic domain, magnetic domain has a strong magnetic. The main reason for the magnet to attract iron is that the iron itself forms a magnetic domain. Ferromagnetic material magnetization, the internal magnetic domain will be neatly arranged together, so that the overall performance of magnetic, which can be attracted by the magnet.
In addition to iron, cobalt, neodymium, nickel, gadolinium and other metals have spontaneous magnetization properties. There is no magnetic domain inside the wood, the atomic magnetic moment in the atoms are offset each other, when the external magnetic field, will produce a small magnetic moment against the external magnetic field, resulting in can not be attracted. Aluminum is a paramagnetic material, magnetic moment arrangement disorder, plus external magnetic field, the magnetic moment tends to coincide with the external magnetic field, but there is no ferromagnetic material is strong, so the general magnet can not attract aluminum.
Magnet in the life of the figure
Magnet, although we can not often feel it intuitively, but it has been integrated into people's lives. For example, compass, magnets, microwave ovens, etc., can also do the engine, magnetic therapy equipment, motors, electric fans of the motor, speakers (speakers), magnetized water. The military field also has its shadow, such as stealth aircraft materials, electromagnetic weapons development research.
Link: The invention of microwave oven and its working principle
Spencer is an electronics genius, microwave oven is his invention. In 1945, Spencer was testing a magnetron, he suddenly found a bit wrong in his pocket, but also heard the hiss. He stopped working on his hand and found that a piece of chocolate in his pocket had melted. Spencer thought, maybe the magnetron fired the microwave to bake the chocolate. Because of this discovery, he immediately thought of the use of microwave can make this phenomenon kitchen appliances. Later Spencer continued to experiment and improve, and finally invented the microwave.
The microwave oven works by heating the water molecules in the food. It is known that the water molecules are composed of two hydrogen atoms and one oxygen atom. Oxygen atoms have a strong attraction to electrons, so the electrons in the water molecules are concentrated on the oxygen atoms side, and the corresponding oxygen atoms are negatively charged, The atom is positively charged.
Usually water molecules are arranged in a mess, positive and negative regardless of direction. When the water is in the electric field, the positively charged side will turn in the direction of the electric field. If it is a static electric field, then the water molecules will be the same as the queue and stop down. If the electric field is constantly turning, the water molecules will continue to follow, trying to keep the same direction with the electric field. If the electric field rotation speed, then the water molecules will be violent vibration, resulting in a lot of internal energy. Water temperature will be increased. General food will be rich in water, so the role of microwave food can be quickly heated or even cooked.