The magnetic principle of electric permanent magnet suction cups.

Whether it is an electromagnetic suction cup or a permanent magnet suction cup, it cannot be separated from the word "magnetic". In fact, as early as the pre Qin era, our ancestors have accumulated a lot of knowledge in this regard. When exploring iron ore, they often encounter magnetite, that is, magnetite (mainly composed of ferric oxide).

Magnetism is a physical phenomenon of mutual attraction or repulsion between substances. Common magnetic substances are iron and magnetite, as well as certain types of steel. Although general substances do not have magnetism, substances in a magnetic field are still subjected to slight magnetic forces, but they can generally be measured using special instruments.

Magnetic force is the fundamental force generated by the motion of electric charges. The Maxwell equations describe the source of this force and its laws of behavior (see also Biot Savart's law). When an electric charge or charged object is in motion, it will generate magnetism. For example, "electromagnetic induction" is a phenomenon that occurs when electrons move in a circuit; And 'permanent magnet' is a phenomenon caused by the fixed spin motion of subatoms in electrons.

The intensity of the electromagnetic field will rapidly decrease as the distance from the source increases. Electric fields are easily isolated by metal shells and reinforced concrete buildings. Power equipment such as transformers, due to their metal casing, have almost no external electric field. Magnetic fields are difficult to isolate, but the magnetic fields generated by currents in opposite directions and of the same size can cancel each other out. Therefore, the magnetic field generated by three-phase power lines is much smaller than that of single-phase power lines.