20190320

Online reading assignment: circuit analysis

Physics 205B, spring semester 2019
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 circuit analysis.


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.
"In a series the current must pass through the resistors in sequence while in a parallel, portions can pass through separately and independently."

"There are two types of configurations for equivalent resistances and they each have a different way of calculating them. First, if there is a series configuration--meaning that the resistors are connected in a chain pattern--to calculate the resistance all you do is add them. Secondly, if there is the parallel configuration, to calculate the resistance you take the inverse of each resistor and add them up, and invert the resulting sum."

"When the resistors are in series, more resistors would mean that the resistance increases; however, when the resistors are in parallel, more resistors would mean that the resistance decreases, which is good for an ideal circuit."

"Current conservation (what flows in must also come out). Current leaving a junction must equal current entered."

"I get the basic concept of what goes in must come out. Any potential increase has to equal the potential drop that occurs from the current flowing through the resistors and bulbs."

"Resistor drops downstream and rises upstream. Emf rises during 'power ups,' drops during 'penalties.'"

"If we follow a complete loop in an electric circuit such that we wind up back at our starting point all the electric rise this potential added together will equal of electric potential that dropped together. This is having the same location as the final and initial points travel in a complete Loop forming an electrical circuit."

"How resistors are connected in series and in parallel and the equivalent resistance calculations. I also understood Kirchhoff's rules."

"I am beginning to understand voltages and currents but I need more practice using Kirchoff's rules."

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.
"Kirchoff's junction rule and loop rule are both confusing. Might need some examples in class to clarify."

"I am still wrapping my brain around why the series and parallel resistors are so different."

"I was a little confused how when resistors are connected in parallel the equivalent resistance is smaller than either resistor."

"I am confused about emf rises/drops with respect to the battery terminals and resistor rises/drops with respect to current."

"I am hazy about voltage potential difference drop and electric potential decrease when the circuit moves from positive to negative. Also voltage potential difference and electric potential increase when the circuit moves from negative to positive."

"I understand the basic concepts, but I think I could use some practice with the actual calculations and logistics of what happens when in regards to the potential and traveling in directions in a circuit."

"I found everything very interesting and understand just about everything in this presentation."

"I don't understand most of this terminology."

"Sorry, so much chemistry."

Determine what happens to the following parameters as current flows through an ideal wire.
(Only correct responses shown.)
Current: remains the same [59%]
Voltage: remains the same [45%]

Determine what happens to the following parameters if you go through a resistor along the direction of current.
(Only correct responses shown.)
Current: remains the same [34%]
Voltage: decreases [59%]

Determine what happens to the following parameters if you follow a path (regardless of current direction) into the (–) terminal and out of the (+) terminal of an ideal battery.
(Only correct responses shown.)
Current: remains the same [45%]
Voltage: increases [55%]

Briefly explain what quantity is conserved when applying Kirchhoff's junction rule.
"Current (amperage) is conserved."

"Charge flow per time is conserved."

"The quantity of current flowing into a junction is equal to the quantity of current flowing out of the junction."

"I think it is 'what goes in must come out' which apparently seems like a simple concept but is useful to enforce mathematically as well to analyze electrical circuits."

Briefly explain what quantity is conserved when applying Kirchhoff's junction rule.
"Electric potential is conserved."

"Energy per charge."

"Kirchhoff's loop rule: the conservation of electric potential (electric potential energy per charge). The sum of voltages around any closed loop in a circuit must equal zero (charge conservation and conservation of energy)."

"No idea."

Ask the instructor an anonymous question, or make a comment. Selected questions/comments may be discussed in class.
"I was following this up until about halfway then I started to get lost with these concepts."

"I am still a little hazy on some of the topics, but I really liked that there were some smaller pictures in the presentation that gave us examples of what was happening while we were reading the descriptions. That really helped and I liked the way it was set up :)" (Hopefully those pictures are what's in your head from now on when you visualize what's going on with the currents and potential rises/drops in circuits.)

"Hi, sorry I was studying for a chemistry test and pretty much just remembered about this assignment at the last minute. :/ "

"I thought I had a good understanding until I saw these examples. The amount of current in must eqaul the amount of current that out of a voltage source. Same goes for the potential difference, the sum of the electric potential rises must equal the sum of the electric potential drops." (That sounds pretty good, so far.)

"Is there anything covered early this semester that will not be on the upcoming midterm? (The study guide for the midterm next Wednesday is already up (five key topics, anything not listed will not be on the midterm), and for this weekend relevant practice problems have been assigned for you to work on, before our review session next Monday.)

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