How to determine the direction of the electromagnet

An electromagnet is a device that is energized to generate electromagnetism. A conductive winding that matches its power is wound on the outside of the iron core. This current-carrying coil is magnetic like a magnet, and it is also called an electromagnet. We usually make it into a bar or hoof shape to make the core easier to magnetize. In addition, in order to demagnetize the electromagnet immediately after power off, we often use soft iron or silicon steel material that demagnetizes faster. Such electromagnets are magnetic when energized, and disappear when the power is turned off. The electromagnet is widely used in our daily life, and the power of the generator has been greatly improved due to its invention.

The direction of the magnetic field of an electromagnet can be determined using Ampere's law.

Ampere's law is a law that expresses the relationship between the direction of the magnetic field lines of the current and the magnetic field excited by the current, also known as the right-hand spiral law.

(1) Ampere's rule in the energized straight wire (Ampere's rule 1): Hold the energized straight wire with the right hand, with the thumb pointing in the direction of the current, and the four fingers in the direction of the magnetic field lines around the energized straight wire.

(2) Ampere's rule in the energized solenoid (Ampere's rule 2): Hold the energized solenoid with the right hand, so that the four fingers are bent in the same direction as the current, then the end pointed by the thumb is the energized solenoid the N pole.