pp. 448–451. Electric Circuits. You will need to read this long section carefully, both because it has practical importance and because we will address it in class.
pp. 448–449. “Series Circuits.” Lots of stuff here. You will understand the important points if you can answer:
Recommmended workbook exercise: p. 93.
pp. 449–450. “Parallel Circuits.”
Recommmended workbook exercise: p. 94, questions 1 and 3. Question 2 is impossible—all three circuits are equivalent as far as I can tell, never mind the “answer” on page 174.
For more challenge, try p. 96 in the workbook. Think of ways to group resistors that together behave like a single resistor. In part d, use the symmetry of the circuit to help you determine how it behaves.
pp. 450–451. “Parallel Circuits and Overloading” and “Safety Fuses.” Practical application of what you have just read about parallel circuits. We won’t address the application explicitly in class, just the principles.
Why are the effects of additional resistors so different in series and parallel circuits?
There’s a ton of stuff here; we will only be able to scratch the surface. Magnetism is a familiar phenomenon, but it is devilishly hard to understand! We will do our best.
p. 458. Introduction. Read this; it is interesting history and it doesn’t take very long. We will not go into it in class.
pp. 458–459. Magnetic Forces. Skim this. It doesn’t tell you much other than that magnetism depends on movement of electric charges, which is a warning of what is to come.
p. 459. Magnetic Poles. Read this to find:
pp. 460–461. Magnetic Fields.
Don’t worry about the relativity stuff, but go ahead and read it. It is interesting.
pp. 461–462. Magnetic Domains. This is beyond the scope of this course, but is does explain how permanent magnets work. If we had two semesters for this course, we would address this. We don’t, so we won’t.
p. 463. “Magnetic Therapy” box. Even though we won’t address this in class, please read this box. It is something that everyone should understand.
p. 464. Electric Currents and Magnetic Fields. A moving electric charge creates a magnetic field. Since a current is just a stream of moving electric charges, a current produces a magnetic field.
pp. 465–466. “Electromagnets” and “Superconducting Electromagnets.” Skip.
Recommmended workbook exercise: p. 97, questions 1–6.
A magnetic field describes the force on a magnetic pole. An electric current produces a magnetic field. The shape of the current’s path affects the shape of the magnetic field. So, in what direction will the force be exerted on a dipole magnet that is located:
How will these forces be affected if the current increases or decreases? If the current reverses direction?
Copyright © 2008, Richard Barrans
Revised: 11 January 2010. Maintained by Richard Barrans.
URL: http://www.barransclass.com/astr1070/rguides/P1050F10rg_04-08.html