AP Physics C - Circuit Analysis
ฝัง
- เผยแพร่เมื่อ 10 ก.ค. 2024
- A brief introduction to circuit analysis and Kirchhoff's Rules for students in algebra and calculus-based physics courses such as AP Physics B, AP Physics 1, AP Physics 2, and AP Physics C. For more information, please visit APlusPhysics.com.
![[4K] BABYMONSTER(베이비몬스터) “FOREVER” Band LIVE Concert “영원히” 베몬만을 사랑하게 되…💗 [it’s KPOP LIVE 잇츠라이브]](http://i.ytimg.com/vi/TQfC0xdpiw4/mqdefault.jpg)
honestly your damn VIRP table may save my ass for my physics test tomorrow. It seems really helpful
Let's hope...
You're welcome -- glad they're helping you out!
It's 3 AM and I'm here only to pass my physics 2 final. Thanks for the lectures. I really can understand now.
In building the circuit diagram I try to show the positive and negative side of each element. Batteries force a potential difference (typically increase), so they go from negative to positive (along the direction of current flow). Potential drops in the direction of current flow across a resistor, so they go from + to -. Then, when you use KVL, as you go around your loop, choose + or - based on which sign you see first for each element!
your videos are so easy to understand, thank you so much
Glad to hear it!
Thank you sooo much this was so helpful!
I don't even learn physics from my teacher, my entire class just considers Mr. Fullerton our teacher
Hi Adrian. I suppose the important part is that you're learning it? Best wishes on a great spring!
You're welcome!
So what would the current be during the example at 22 minutes in each of the branches on the bottom that have no resistors be? (The wire connecting to the negative terminals of each battery)
On the left hand side, it would be I1 (whatever enters must leave, KCL) and on the right-hand side it would be I2 (same reasoning).
Thank you so much!
Hello, sir, I have one question here. When we analyze circuit with multiple batteries by using Kirchhoff's node rule, how do we determine the node equations at first if we don't know the direction of the current in different branches? Although people say our choice of the arrow directions is arbitrary, how do we find out at a certain point which current is coming in and which going out?
Hi Dan,
At 17:19 in the video you say that proceeding clockwise and seeing negative side of battery first the voltage displacement is - 12 V, moving across the resistors you denote the voltage displacement with + signs. Shouldn't it be the other way around? Since your starting at the negative terminal of the battery, doesn't the voltage go up as you reach the positive side (+12V). That has me a bit confused. Similarly since the move is in same direction of current, shouldn't it be -IR? Thank you very much I really appreciate the help you provide to AP Physics C students.
You can do it either way. I was taught in engineer school to add up the voltage drops (so you record the sign of whatever side you see first). Others do the opposite. Since they all sum to zero, you get the same answer regardless.
Yea that's true, it doesn't affect the answer and it's a pretty neat "trick" that helps avoid confusion. Once again, thank you very much!!
why are the voltages through the batteries - while the voltages through the resistors are +? do you have a video on dipole moments? thanks
Thanks sir,appreciated!
You don't have to know the node equations. Draw an arrow on your schematic and label it I1, I2, etc. Take your best guess as to the current's direction when you draw your arrow for current. Then, go ahead and do all your analysis. If you end up getting a negative current, that means the current is actually going opposite the direction of your arrow!
Can we use VIRP table for two voltage sources or more?
If yes, it would be really great to see an example.
Thanks for everything, sir!
+SystemsEngineering Hi! You can, but it's a bit more complex of a process and not as straightforward. Once you get to multiple voltage sources I tend to find that students have enough of an understanding of circuit elements that they no longer need the VIRP tables. :-)
Hi dan.. I know its late but could you explain how you used kirchoffs law on the last problem to say I1 plus I2=I3
Ben Eckardt Sure. Kirchhoff's Current Law states that the current entering any point in the circuit must be equal to the current leaving that point in the circuit. Looking at that top middle node, I1 and I2 come in, and I3 leaves, so I1+I2 must equal I3. Conservation of electric charge.
Have you ever considered using a RIVP table instead? I used to use VIRP tables with my physics classes, but I changed to RIVP tables. This sets up the columns so that the first two multiply together to give the 3rd column, and the 2nd and 3rd columns multiply together to give the 4th one. I find that it makes keeping track of the variables a little easier. Besides, you pronounce RIVP so that it sounds like "ribbet", which links back to Galvani's frog.
I hadn't, but that sounds just as fun to say and the 1/2 and 2/3 multiplying sounds cool!
is the combination of series/parallel circuits included on the AP1 exam?
yes
apcentral.collegeboard.org/pdf/ap-physics-1-course-and-exam-description.pdf
We need the node equation before we calculate current and determine its correct direction, but since I don't know where different currents flow, I cannot get the correct node equation (i.e. I 1 + I 2 = I 3 rather than I 2 + I 3 = I 1)
Hi at 17:07 how do you know which arrows point up or down?
You don't. You pick a direction, and if your current works out to be negative, then the current flows in the opposite direction of the arrow you drew.
So does this topic of this video, if its title says "AP Physics C", apply to the Physics 1 exam?
Yes, but it's a bit more in depth than needed for AP Physics 1. Instead, may I recommend the AP Physics 1 video on series and parallel circuit analysis? th-cam.com/video/JNpnjfBFCyo/w-d-xo.html and th-cam.com/video/zAGrHdSI7fM/w-d-xo.html
Of course! and Thanks Mr. Fullerton!
I just want to say Thank you !
+Tan Ben You're very welcome!
+Dan Fullerton (APlusPhysics) Hi Mr fullerton, i just took a test and instead of 2 voltage i am given 3 voltage and 3 loops. How do i define the direction of the current? How should i proceed should I always start at the bottom or is there any convention on how to start KVL in this case?
+Tan Ben Hi Tan -- no real convention, just start writing various KVL equations and then use your algebra skills to determine the unknowns. As for direction of current, just pick a direction and draw the arrow on your circuit. If you get a negative current when you solve, then the current through that branch is opposite the direction you've drawn.
+Dan Fullerton (APlusPhysics) Thank:) you clear my doubt
You're welcome!