PHYSICS 142L Study Guide - Midterm Guide: Optical Fiber, Inductor, Force It
15 Sep 2016
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Document Summary
Magnetism is a difficult concept to define explicitly, but one definition is as follows. Magnetism is a property of materials that can be influenced by the presence of a magnetic field, which is a type of "field of influence" caused by moving charges and magnetic materials. Every magnet, regardless of its shape or size, has two poles, north and south which exert forces on one another in a similar manner to electric charges - similar poles repel, opposite poles attract. Magnetic poles always come in pairs (unlike charge, a single pole has never been isolated). The force between two poles is proportional to the inverse square of the distance between them. Magnetic fields exist around permanent magnets and moving charges, and have the following properties: By definition current is moving charge, and so current induces a magnetic field; in this context magnetic field is often referred to as magnetic induction.
