Cuesta College, San Luis Obispo, CA
Students have a bi-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 magnetism and magnetic forces from fields.
Selected/edited responses are given below.
Describe what you understand from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically demonstrate your level of understanding.
"I am understanding a lot better the relationships between current and the resistance in series and parallel circuits after going over and over it for the quiz. I also find greater understanding of the measurements of the ammeters and voltmeters."
"Magnetic fields of a magnet leave through the north pole and form a looping path and return through the south pole."
"In a direct model a source magnet exerts a force on the test magnet. It will attract if the poles are opposite and repel when they are the same."
"There are two ways to approach the direction of magnets. For the direct way, the source magnet exerts a force on the test magnet. The indirect approach requires two steps, the source magnet creates a magnetic B field everywhere around it, and then the B field exerts a force on the test magnet."
"We label the two magnets that exert forces on each other as 'source' and 'test' poles, where the source magnet is said to be exerting a force on the test magnet (with a north and a south pole). For a field model, instead of a source magnet directly exerting a force on a test magnet, in this two-step model, the source magnet is said to create a magnetic B field everywhere around it, and it is this magnetic field that exerts a force on a test magnet."
"North repels north, but attracts south. Vice versa. Source magnet creates B field, B field exerts force on test magnet. If another magnet enters the field the force is exerted opposite of the lines of the field."
"Magnetic fields are created by magnetic sources and that these fields behave similarly to electric fields in the way that they affect test magnets, currents, and charges. Magnetic field lines move away from the north pole, towards the south pole, and through the magnet back out of the north pole."
"Magnetic force is always perpendicular to both magnetic field and the velocity. Whereas the force applied by an electric field is always parallel or antiparallel to the field direction. "
"I understand the right-hand rule now that I actually wrote them on my right hand rather than the left. I understand that this right-hand rule shows the direction of the magnetic force and that the middle finger will show the direction properly if the thumb is pointing on the velocity vector and the index is on the magnetic field lines, but I think this only works for positive particles. The left-hand rule is used for for magnetic forces on negative charges."
"Hidden Dragon. Crouching Tiger. Hidden Dragon. Crouching Tiger. And 'very bad finger.'"
"Single-pass generators can only be used once before having to be reset, while continuous generators do not have to be reset and they then provide continuous emf and current. A Faraday disk is an example of a continuous generator when cranked."
Describe what you found confusing from the assigned textbook reading or presentation preview. Your description (2-3 sentences) should specifically identify the concept(s) that you do not understand.
"I was a bit confused on the magnetic fields. I am just having trouble with figuring out where the magnetic field is and how to find it."
"Why magnetic field lines loop from north to south. The right hand rule."
"I find confusing the RHR1 and RHR2 based on how to use them!"
"I do not understand the hand things."
"Everything was relatively easy to understand except the RHR1, I didn't understand that."
"I didn't understand how field models work."
"I would benefit from a walkthrough on field models just to make sure I understand the concept."
"I just need a class lecture on this to understand better. I'm confused on how to point which finger where."
"Can you explain the right-hand rules a little bit more? I would really benefit from that in class."
"Not super sure what the right-hand rules symbolize."
"I'm so confused on angle theta and what the angle is measuring. Tomorrow I really want to get through what theta is and what RHR1 means for the 'Hidden Dragon, Crouching Tiger,' because trying it at home made no sense for me."
"I'm still confused on how to properly use the 'Hidden Dragon, Crouching Tiger' hand signs."
north; south. ************************** [36] south; north. * [1] (Unsure/guessing/lost/help!) *** [3]
Inside of a bar magnet, magnetic field lines travel from the __________ pole to the __________ pole.
north; south. ********** [10] south; north. ************************* [25] (Unsure/guessing/lost/help!) ***** [5]
State the symbol used for the magnetic field, and the SI units for magnetic field strength.
"B; teslas [T] or [N·s/C·m]."
"B; teslas [T] or gauss, where 1 tesla = 10,000 gauss."
"The symbol used for magnetic field is F with an arrow over the top; the SI units used is newtons?"
(Only correct responses shown.)
B finger and F finger: exactly 90° only [35%]
v finger and F finger: exactly 90° only [35%]
In general, the direction of the force of a magnetic field on a moving charged particle will be along the:
particle's velocity vector. ** [2] the magnetic field line. ****************************** [30] (Neither of the above choices.) ** [2] (Unsure/guessing/lost/help!) ****** [6]
Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I need more explanation on right-hand rules please."
"I think we need several in-class examples using the right-hand (and left-hand) rules."
"Physics gang signs... (laughing inside)."
"Magnets are cool! :)"
"I get a little confused when it comes to the magnetic fields and the whole idea around it."
"I just think this material is more difficult to understand from the readings so hopefully class will clear up some confusion."
"After finishing the resistance lab last week, we tried to use a number of batteries from our calculators to see how bright the light bulbs can get and home many bulbs (connected in series) we could light with the batteries that we have."
"YOUR CLASS IS TOO DIFFICULT."
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