The number of coil turns of a conventional strong electromagnet depends on the size of the iron core of the strong electromagnet, the power supply voltage (and the type of power supply DC or AC), the resistance of the enameled wire, and on a well-designed strong electromagnet, increasing the number of coil turns may increase some electromagnetic force , but is quickly limited by the reduced current and saturated core. The number of turns of the electromagnetic coil of strong electromagnet and the greater the current passing through the coil, the more magnetic flux generated and the stronger the magnetism, but when a certain number of turns and current are reached, the magnetic flux is in a saturated state, that is, if the coil is increased again The number of turns or current, the magnetic strength will not increase any more.​​

A device with an iron core inside that uses a coil with current to make it magnetic like a magnet is called a strong electromagnet. Usually made in bar or hoof shape. The iron core should be made of soft iron or silicon steel that is easy to magnetize and easy to lose magnetism. Such a strong electromagnet is magnetic when energized, and disappears when it is de-energized. strong electromagnet is widely used in daily life. The invention of strong electromagnet has also greatly improved the power of the generator.​​
When the iron core is inserted inside the energized solenoid, the iron core is magnetized by the magnetic field of the energized solenoid. The magnetized iron core also becomes a magnet, so that the magnetism of the solenoid is greatly enhanced due to the superposition of the two magnetic fields. In order to make the strong electromagnet more magnetic, the iron core is usually made into a hoof shape. However, it should be noted that the winding direction of the coil on the shoe-shaped iron core is opposite, one side must be clockwise, and the other side must be counterclockwise. If the winding directions are the same, the magnetization of the two coils on the iron core will cancel each other out, so that the iron core is not magnetic.
In addition, the iron core of the strong electromagnet is made of soft iron, not steel. Otherwise, once the steel is magnetized, it will remain magnetic for a long time and cannot be demagnetized, and the strength of its magnetic properties cannot be controlled by the magnitude of the current, and the advantages of strong electromagnet will be lost.