A Geek Girl's Guide to Electronics and the Internet of Things by O'Shea Audrey;

Author:O'Shea, Audrey; [O’Shea, Audrey]
Language: eng
Format: epub
Publisher: John Wiley & Sons, Incorporated
Published: 2020-10-06T00:00:00+00:00

The Electricity/Magnetism Relationship

To review the relationship between electricity and magnetism, we first must discuss magnetism.

Magnetism

The first question to answer is, what is magnetism? Magnetism is an invisible force that exists around certain objects, called magnets. Just like electricity has an electromotive force (EMF), a magnetic field's push is called magnetomotive force (MMF). The area encompassed by this force is called a magnetic field, and it will attract only certain metals. Iron, nickel, and cobalt are naturally occurring ferromagnetic materials, meaning they are easily magnetized. Most material that is ferrous (i.e., containing iron) is attracted to a magnet, although not all alloys are.

Magnetism is caused by the molecular alignment of atoms in a material such that at any given time the positive and negative forces of a group of atoms are aligned with each other. These groups of aligned atoms are called magnetic domains. See Figure 11.1. In a magnet, the magnetic domains are aligned in the same direction. A common screwdriver can be turned into a magnetic screwdriver by stroking it with a magnet in a single direction to align the magnetic domains. Ferromagnetic materials can be turned into magnets by subjecting them to a strong magnetic field for a time. Lodestones, which are made of the mineral magnetite, are naturally occurring magnets and have been used for thousands of years. Neodymium is a rare Earth metal that is used to make some of the strongest magnets on Earth.

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