In this lesson our instructor talks about magnetism. First, he discusses dipole, monopole, magnetic fields, and moving charge. Then he talks about magnets on an atomic level, current, electric motor, and generator. Three complete example videos round up this lesson.
Every magnet comes with two poles. Just like electricity, like poles repel each other, while opposite poles attract.
Like electricity, we can describe the space around a magnet with a magnetic field and visualize it through the use of magnetic field lines.
Unlike electricity, it is not possible to separate these poles from each other. Magnets always come as a dipole: two poles together.
Moving charge creates a magnetic field.
On an atomic level, all atoms involve moving charge (the electrons). Thus, they have many small magnetic fields. Normally, the random distribution of these fields results in no net effect.
However, in some materials (such as iron), it is possible for these magnetic fields to all align and create a temporary or permanent magnet.
Since moving charge creates a magnetic field, we can run current through a wire to create a magnetic field in the space around it.
Through some clever arrangement, we can run current through some loops of wire, create a magnetic field, and then have it interact with another magnetic field, causing those loops to spin. Spin them with enough force, and you've got an electric motor.
The reverse also works: a changing magnetic field induces a current in a conductor. If you place a loop in a magnetic field and make it spin with enough force, you've got an electric generator.
Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.
This book includes a set of features such as Analyzing-Multiple-Concept Problems, Check Your Understanding, Concepts & Calculations, and Concepts at a Glance. This helps the reader to first identify the physics concepts, then associate the appropriate mathematical equations, and finally to work out an algebraic solution.