Circuits Definition and 1000 Threads

  1. M

    Parallel and Series circuits and current

    Homework Statement 2 different questions that I'm using to test my understanding of the physics concepts rather than the math: 1) How does the brightness of bulb A compare to that of bulb C? After D is added how does the brightness of bulb A change? Does the brightness of B change? Does...
  2. G

    MHB Logic Circuits and Truth Tables

    Hey guys, I'm in a pickle with this question. Its really not my cup of tea, its a struggle factor really but I don't really have a choice whether I like it or not. A worked example such as this allows me to see what it is I need to do. If anyone can provide a helping hand it would assist me...
  3. S

    Help needed with concept of electricity, magnetism and EM

    Hi, so I've just started learning about physics and I get the gist of most of it. I understand motion, torque, energy, light, radioactivity. But there is one topic that absolutely stumps me. Electricity. Can someone explain to an absolute moron like me what it is? It seems like everyone around...
  4. BarelyOtaku

    Engineering RC circuits, a step skipped in solution

    Homework Statement . [/B] This is problem 7.45 in Fundamental of Electric Circuit 5th edition. 2. Homework Equations First off, I want to go ahead and say that I don't need the solution I already solved it. I went ahead and used Nodal analysis when Vs = 30. I placed a node voltage right...
  5. E

    Length contraction test in electrical circuits

    As I am sure everyone is aware, there are still folks who don’t believe SRT and GRT. While 99.9% of them are nut-jobs, there is at least one that I respect – Tom Phipps specifically. I am not familiar with any of his writing before the advent of the GPS satellites. In any case, he now accepts...
  6. lfqm

    Introduction to superconducting quantum circuits

    Hi guys! I'm making my Phd on cavity QED but wish to move towards superconducting quantum circuits, could you give me some good references (articles or books) at an introductory level (for self-study)? Thanks in advance
  7. B

    Engineering Finding the Second Constant in an XRLC Circuit Current Response Problem

    Homework Statement FIND i(t). [/B]Homework Equations VL = L*(di/dt) (Equation 1) IC = C*(dV/dt) (Equation 2) I(t) = e^-9*t*(A*cos(4.359*t) + B*sen(4.359*t)) A (Equation 3) The Attempt at a Solution I can get the exact value of the constant B as shown in the answer if I use -6 after the...
  8. S

    Will this circuit work? what am i missing?

    hi, so i want to be able to run a motor depending on whether or not an IR detector senses IR light. so the basic idea at the start was to connect the motor with the detector and a resistor in series and therefore if there is IR the current will flow turning on the motor. I then learned that the...
  9. F

    Electric Potential Energy Conversion

    Hello everyone, Imagine two points that have a Electric Potential Difference of 10V and they are connected through a conductor wire. Let's call these points A and B: Now imagine we have a charge on A of 1C. To move the charge to B, we need to make a work of 10J, right? So, now, imagine the...
  10. M

    How does voltage work in a circuit and why does it drop through resistors?

    I have a few questions about how a series circuit works. I've attached a picture of a series circuit on this post. First of all I'm a little bit confused about voltage. If I'm correct, voltage is electrical potential. For example there is a voltage between two electrons being pushed close...
  11. T

    Engineering Can you help me solve this circuit problem using linear algebra?

    Hi I got stuck at the following circuit problem which involves linear algebra, since I am not a physics major, I don't even have the basics to get started. Please shed some light, really appreciate it! Thanks a lot. 1. Homework Statement Consider a long chain of resistors wired up like this...
  12. Dethrone

    MHB Op-Amps Circuits: Explaining Prof's Method

    Can anyone explain to me what my professor did? I am able to get the same answer, but not without a page of nodal analysis. It seems quite elegant and none of my friends know what method she used. Thanks!
  13. S

    RC Circuits, how do you solve for V(infinity)?

    Homework Statement Question is attached below Homework Equations v(t) =v(infinity) + [v(t0)-v(infinity)]e^[-(t-t0)] The Attempt at a Solution For t<0, you get the circuit where it is only Rt, R, and C, but in dc circuits, the capacitor is an open circuit, does this mean v(t0) =0? For t>0 the...
  14. C

    V-i characteristics for voltage divider with current source

    This is a problem from Foundations of Analog and Digital Electronic Circuits by Agarwal & Lang, I'm going through it by myself, I'm not in a course, so I'm depending on you friendly forum people for help! I really like this book but it has a lot of errors, perhaps this is another error. 1...
  15. R

    Change in total energy of capacitance

    Homework Statement When an initially charged capacitor is connected in a circuit with an uncharged capacitor, why would the total energy of both capacitors be less than the initial energy of the charged capacitor? Homework Equations This was a question asking for an explanation, so I'm not...
  16. davenn

    Parallel RL Circuits: Uses & Impedance Matching

    This query comes from not being able to answer some one else's query :oops: it show's I have been away from textbooks and classrooms way too long ( see my signature ) I have forgotten my basics These RL circuits Now I realize A and B are just the same with the RL rotated and following that...
  17. Feodalherren

    Engineering Circuits: cascading op-amps, general question

    Homework Statement Solve for final Vout. Homework Equations Circuits The Attempt at a Solution So 1 and 2 are easy. I'm just going to skip to where I get confused. There is a 50k resistor between where I solved for Vout after the 2nd Op Amp. I found the voltage to be 12V. Now the solutions...
  18. D

    Lab Report- Circuits Calculating Resistance and Current

    I am struggling with doing calculations for a physics lab report. I understand how to calculate the equivalent resistance and the voltage of the battery. I am struggling with calculating the resistance of each resistor and the current of each resistor. I am sorry but I am getting very...
  19. C

    How can we distinguish between different types of PCB?

    they have different names or something else?
  20. B

    Differentiator/Integrator circuits: Op-amp vs RLC circuits

    It is possible to use a capacitor/inductor in an op-amp to allow it to perform the mathematical function of differentiating or integrating an input signal. It is also possible to do this without an op-amp, using simply resistors, inductors and/or capacitors. So what are the advantages of using...
  21. A

    Question about the properties of inductive circuits?

    I'm studying for my prelim and am trying to understand inductance better based on some questions I have done I've come up with these statements can anyone confirm they are true the back emf in an inductive circuit at any given time equal to the voltage across the inductor I initially thought...
  22. A

    Inductor Role in Time Constant of a DC Circuit

    A d.c circuit consists of a switch, lamp and inductor. The inductor is replaced with an inductor with twice the number of turns in the coil of wire, nothing else about it is changed. State the effect on A) maximum current B) the time to reach max current I thought increasing the turns would...
  23. J

    RMS in AC Circuits: Why Use Square for Mean Values?

    Why do we use the square of the graph as opposed to the absolute value of the graph to find the mean values?
  24. T

    Thevenin and Norton equivalent circuits

    Hi guys, Sorry if all you guys think this question is too easy. But I have a hard time to understand how to group the resistor. I suppose to find the the thevenin and Norton equivalent circuit. This is what i think about the combination of resistor. Req1= RL+1k Req2= Req1 ll 3.3k (3.3k after...
  25. P

    Power dissipated by a resistor in a circuit

    Homework Statement Homework Equations P = V^2 / R 1/Rt = sum(1/Ri) (parallel) The Attempt at a Solution [/B] Since all the answer choices express the solution in terms of V^2 / R, I tried to find the voltage drop across resistor #2 to find the power. I collapsed the two parallel...
  26. K

    Engineering XOR Gate Circuits: Draw Z with Lowest # of 2 Input Gates

    Z(A,B,C,D) = SUM-M(1,2,4,7,8,11,13,14) Draw circuit of Z with lowest number of 2 inputs xor-gates. Can i have a clue? I tried drawing k map and had too many terms.
  27. jcoona

    Resistors Used in College Electrical Circuits Labs - Any Suggestions?

    I am taking an intro electrical circuits course which requires that I write extensive lab reports. I just completed a really simple lab about calculating resistance when configured in series and parallel, etc. In my intro I'm writing a short explanation about resistance, and resistors, and...
  28. I

    Voltage generators in open edges and Thevenin's generator

    Homework Statement I hope you can see the picture clearly. Someone drew lines over it,so please try to ignore that. The problem here is to determine the current of ideal current source Ig, if following parameters are known: -E1=50V, E3=30V -R1=200Ω, R2=500Ω, R3=3kΩ, R4= 10 kΩ -C=0.7 μF...
  29. 2

    Engineering Finding equivalent resistance for the given circuits

    Homework Statement Find the equivalent resistance Rab for each circuit given here (resistance values have been omitted so I can focus on understanding the concept, but I can supply them if requested). Homework Equations This problem expects me to know how to combine resistors in...
  30. P

    Potential difference across two points in a circuit

    Homework Statement [/B] Find the potential difference between points b and a in the circuit below I have already solved for the voltages of the two batteries (1 and 2) in the circuit (18 V and 7 V respectively) 2. Homework Equations Kirchhoff's Rules 1) Potential difference across any...
  31. I

    Engineering Calculating net change of capacitor charge in a circuit

    Homework Statement This problem apparently has a simple solution if you are good with circuit theorems but no matter what i try or how i combine them, it's just impossible. Given a circuit on the picture, and circuit parameters E3=12V,R1=1kΩ,R2=30Ω,R3=150Ω,R6=200Ω, if it is known that current...
  32. O

    Understanding Snubber Circuits: Benefits & Differences

    may i know what is snubber circuit?? and what is the different between having snubber circuit vs without subbers circuit..
  33. 2

    Engineering Question about dc to ac circuits in solar panels?

    Homework Statement It can be shown that a square wave can be represented by a sum of sine waves as given by the formula below v = v0sinωot + v1sinω1t + v2sinω2t + v3sinω3t +... Solar cells have an output that is dc. The pd across a cell depends on the incident radiation and the efficiency of...
  34. thegreengineer

    Basic Electronics: Transistor confusion

    So, recently I started learning about electronic components and then I started learning about semiconductors. The one which I've been having some real trouble to understand its function is the transistor. So I bought an electronics textbook called El ABC de La Electrónica (The ABC of Electronics...
  35. B

    L-R-C Series Circuits - Help With Differential Equation

    Hello, this is a maths problem that is related to a physics problem, but I think it's best posted here due to what I'm asking about. 1. Homework Statement \frac{d^{2}q}{dt^{2}} + \frac{R}{L} \frac{dq}{dt} + \frac{1}{LC}q = 0 is a differential equation describing how charge and current change...
  36. J

    Understand Voltage Drop in Series Circuits: Questions Answered

    Hi all, I have a question about voltage drop of a battery. I understand Kirchoff's laws well, but it occurred to me that I did not understand intuitively why the "zero volts" at the end leg of a series circuit would still produce current. Theoretically you could have the majority of a series...
  37. J

    Engineering I thought circuits had to be closed

    Homework Statement I am supposed to determine the potential differences between the points. However, I thought circuits had to be closed...
  38. U

    Electrical Potential between 2 points

    Mentor note: Member warned about posting a question without the template 1. Find the electrical potential between A and B given that R1=R2=R4=100 Ohms; Power dissipated by R3 is 200 mW at 9 Volts [ code ] A---------R1-----------*------------------- | |...
  39. S

    Why is ABCDEFA considered a closed loop even with the presence of conductor BE?

    Homework Statement So this is not really a 'solve this problem' question, but, rather, I am trying to understand how they can call ABCDEFA a 'closed loop' even though there is another connection (BE) inside it, and why the equations work. Keeping in mind that I am still in high school...
  40. H

    Engineering Delta and star transformation of AC circuits

    Homework Statement For the balanced three-phase loads shown in FIGURE 3, ZY = (15 + j15) Ω and ZΔ = (45 + j45) Ω. Determine: Uploaded file C1.png (a) the equivalent single Δ-connected load, (b) the equivalent single Y-connected load obtained from the Δ-Y transformation of (a) above, (c) the...
  41. M

    Solving Electrical Circuits: V1 & V2 Equations

    Homework Statement Homework Equations 3. The Attempt at a Solution Z11 8 + 6 Z12 6 Z21 6 Z22 6 V1 = Z11 I1 + Z12 I2 V2 = Z21 I1 + Z22 I2
  42. thegreengineer

    Electric circuits formulas doubts

    Well, recently I have started to deal with electronics and I've seen several new concepts such as ohm's law, parallel and series circuits, what's AC and DC and many other topics. Ok, I have no doubt on what's direct and alternate current or what a series and parallel circuits are; rather than...
  43. N

    Engineering Coupled RC circuits with AC current source

    Homework Statement Hi, I already asked a question close to this, but now I have different conditions. This is the circuit C_1 = C_2 \\ R_1= R_2 The current is an AC , and I would like to know the voltage at R_1 and at R_2 I made some progress but I do not really know hot to continue...
  44. L

    How to redraw circuits in this problem to see series/paralle

    Homework Statement See pic for problem statement and diagram (we are dealing with the diagram on the right) http://i.imgur.com/Uv7Ikma.png I'll rewrite the problem statement here if that helps: Find R_T in the diagram for the cases where ab is open circuited and short circuited. And its...
  45. ranju

    Understanding Three Phase Circuits: Direction of Arrows

    In the given figures , what does the arrows denote , I mean what direction ?? VnR is upward in 1st fig. , VnR is towards left in 2nd fig. ( n is neutral here ) while in 3rd the line voltages are in anti-clockwise direction..! I wanted to know the pupose of this and why these directions only??
  46. ranju

    Polyphase Circuits: Purpose & Benefits

    Apart from single phase circuits , we use two phase , 3 phase mostly .. but I want to know what actually we mean by 2 phase , 3 phase circuits..! I know in single phase supply , there is one voltage , one current .. 3 phase has 3 currents and voltages.! What is the purpose for these polyphase...
  47. L

    Engineering Understanding how to re-draw circuits

    Homework Statement I need to find I1,I2,I3,Va,Vb but i don't even know to read the circuit. i know how to to do series circuits and parallel circuits but not this. How do i read this circuit and know which ones are in parallel or in series. is there a way to re-draw it? I have the solution...
  48. A

    Engineering Solve Two Circuits: PPG & 2-ch Amplifier | Find KVL, KCL, LED Output

    hi i need help to solve these two circuit as my professor said in university. i must find the value of each part to make these two circuits in pspice and in breadboard. i need the values and KVL and KCL. the first photo is PPG and voltage for each v must be 9 volt and output must be LED. the...
  49. Captain1024

    Help Finding Transfer Function Vo/Vs

    Homework Statement Find ##a)\ H(s)=\frac{V_o}{V_s}## of the filter in the circuit below. ##b)\ ##The center frequency ##\omega_0## ##c)\ ##The band-width B Correct answers: ##a)\ H(s)=\frac{6s}{12s^2+11s+1}## ##b)\ \omega_0=0.28\frac{rad}{s}## ##c)\ B=0.71\frac{rad}{s}##...
  50. I

    Confused about I V tradeoff in circuits

    to skip the introductory part go straight to the question between the hyphens. I wanted some help mending two seemingly contradictory concepts. on one hand we have ohm's law: I= \frac{V}{Z} stating that current is proportional to the potential between two points. makes sense. on the other...
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