Online reading assignment: magnetic fields of current-carrying wires and loops

Physics 205B, spring semester 2013
Cuesta College, San Luis Obispo, CA

Students have a weekly online reading assignment (hosted by SurveyMonkey.com), where they answer questions based on reading their textbook, material covered in previous lectures, opinion questions, and/or asking (anonymous) questions or making (anonymous) comments. Full credit is given for completing the online reading assignment before next week's lecture, regardless if whether their answers are correct/incorrect. Selected results/questions/comments are addressed by the instructor at the start of the following lecture.

The following questions were asked on reading textbook chapters and previewing presentations on magnetic fields of current-carrying wires and loops.

Selected/edited responses are given below.

Describe something you found interesting from the assigned textbook reading or presentation preview, and explain why this was personally interesting for you.

"The movie is awesome! I wish the human eye could see magnetic fields like that, although that might be a little distracting."

"Being able to use my fingers to predict which direction the current, magnetic field, or force is going."

"It was interesting how the iron filings aligned themselves with the magnetic field."

"I found many of the concepts hard to picture, so I don't think I have enough insight to find anything too interesting."

Describe something you found confusing from the assigned textbook reading or presentation preview, and explain why this was personally confusing for you.

"Using the hand rules for cross products--I'm thinking the textbook just overcomplicates it."

"The third right-hand rule is giving me a little trouble. it says your thumb points in the direction of the magnetic field in the interior of the loop, I'm having some trouble visualizing how to move my hand."

"I get confused on when to use a right-hand rule and a left-hand rule."

"Its interesting that the magnetic field in a closed loop is so concentrated in the center of the loop; I suppose that is similar to a bar magnet in that the lines are closest near the magnet but for each line in the center, doesn't there have to be just as many farther out?"

"Even though it isn't confusing when reading about it on your blog, I have a feeling I am going to get easily confused when trying to determine which right-hand rule to use on any given problem!"

Explain the similarities/differences between a circular current loop, and a solenoid.

"The similarities are that the magnetic field lines are concentrated within the loop or loops of wire and so a solenoid is like a series of circular loops. The difference is that a solenoid magnetic field is not dependent upon the radius of the apparatus as seen with a loop of wire."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.

"The magnetic field of a solenoid and a loop do still make closed loops, right?" (Yes.)

"Will you explain the difference between the circular current loop and a solenoid?" (Will do.)