How to use the wire to explain the electromagnetic coil

Many people don't know what the electromagnetic coil is. When it comes to the principle of the electromagnetic coil, it is also confused. Here we will talk about how the electromagnetic coil works!
There is a movable iron core inside the electromagnetic coil. When the valve is energized, the iron core is attracted by the coil and then moved to drive the spool to move, thereby changing the conduction state of the valve. Professionals may have heard of dry or wet, and that is just the working environment of the coil, which is no different for valve action.
But we must know that the amount of inductance is completely different after the air-core coil is added to the core. The inductance of the former is much smaller than that of the latter.
When the coil is connected to alternating current, the impedance produced by the coil is naturally different. For the same coil, when the AC power of the same frequency is added, the inductance will change with the position of the core, that is, the impedance changes with the position of the core. When the impedance is small, the current flowing through the coil will increase.
So how does the electromagnetic coil use the wire to make an effect? In fact, it is built by the presence of a magnetic field around the wire, and it is wound into a spiral to strengthen the magnetic field, so that the minimum magnetic field can be used to achieve the highest magnetic field strength.