What the HECK are Magnets? (Electrodynamics)

This paragraph delves into the nature of electric charge and its relationship with electric and magnetic fields. It begins by acknowledging the support from Patreon and then transitions into a discussion about electric charge being a measure of how something can influence the electric field. The video raises the question of whether there is a magnetic charge that affects the magnetic field, clarifying that while the magnetic field is influenced by electric charge, it is not as straightforward as the electric field. The paragraph explains that a stationary proton only affects the electric field, but when it moves, it can also impact the magnetic field. The concept of directionality in the representation of these fields is introduced, using the visual of orange Xs and dots. The paragraph then discusses the impracticality of experimenting with single charged particles and introduces the concept of electric current, leading to a historical account of key discoveries by Ørsted, Biot, Savart, and Laplace, and the naming of the Biot-Savart Law. The main point is that magnetism arises from moving charges, whether it's a single charge or multiple charges in a current, and this is true regardless of the wire's shape.

This paragraph explores the different types of magnets,区分电磁铁和永磁体, and examines the fundamental properties that govern them. It starts by explaining that an electromagnet is created by electricity, but there is no electric current flowing through a permanent magnet, leading to the question of why it is called a permanent magnet. The paragraph clarifies that these magnets appear permanent due to their long-lasting magnetic properties, which can diminish over thousands of years. The discussion then moves to the basic properties of magnetic fields, highlighting the existence of two opposite sources known as poles, labeled north and south. The concept of magnetic domains is introduced, explaining that even electromagnets have poles if shaped in certain ways. The paragraph emphasizes that magnets always come in pairs and introduces Gauss's law for magnetism. It then poses the question of how materials become magnetic without electric current, leading into a quantum mechanics explanation. The paragraph describes the zooming into the molecular level of iron and the role of electrons in creating magnetism through their angular momentum and spin angular momentum. The video explains that while any electron with non-zero angular momentum can act as a tiny magnet, the cancellation of these effects in pairs means that only certain materials, such as iron, cobalt, nickel, and gadolinium, exhibit magnetic properties at room temperature. The paragraph concludes by reiterating that all magnets, whether single charges, currents, or the spin of subatomic particles, are fundamentally electromagnets.