Circuit Definition and 1000 Threads

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit. Its basic function is to interrupt current flow after a fault is detected. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.
Circuit breakers are made in varying sizes, from small devices that protect low-current circuits or individual household appliance, up to large switchgear designed to protect high voltage circuits feeding an entire city. The generic function of a circuit breaker, or fuse, as an automatic means of removing power from a faulty system is often abbreviated as OCPD (Over Current Protection Device).

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  1. L

    What is the least resistance in this RC circuit?

    Hello, I know that the lower the resistance the lower the charge/discharge time in an RC circuit, i.e. 5RC is about the charge/discharge time for the capacitor. But how small is the resitstance allowed to be? I'm guessing that the lower the resistance the more the circuit looks like it has just...
  2. baywa2

    Determine the capacitor value so that this circuit is in resonance

    L=100mh=0.1H ω=10^3 rad/s -> f = 159Hz XL= ωL= 2πfL= 2π*159*0.1= 99.90 Ω Z parallel = [(XL∠90º)*R2] / [(XL∠90º)-R2]= 37.13∠-21.8º XC= 1/ωC= 1/(2 π f C) I don't see how I am supposed to get to C
  3. P

    I Replace a Toffoli gate with an equivalent circuit

    Hello, I am currently working on this task here. Given is a Toffoli gate. Now it is stated that there is an equivalent quantum circuit. I tried to show the equivalence, for example by looking at case ##|111\rangle##. However, with what I have calculated so far, I do not come to the...
  4. e0ne199

    Engineering Problem about steady-state circuit analysis

    Here is the question, and my solution is for question (a) : knowns : I = 12 cos 2000t = 12 ∠0° L=0.2 H R=200Ω ω=2000, XL = j*0.2*2000 = j400Ω Zt = (j400*200)/(200+j400) = 178.9 ∠26.57°Ω i want to find the power absorbed by R, so : IR = (Zt /R)*I = (178.9 ∠26.57°Ω/200)*12 ∠0° = 10.73∠26.57°A...
  5. J

    Engineering Longest Path in a Combinational Circuit

    First for logic-1 at output: So I get that for Logic 1, the OR-2 Gate must have one input has logic-1. Case1: Upper OR-Input is 1 of second OR Gate. So the longest path is Inv-1, Or-1, Or-2. Delay is 9ns. Case2: For lower input to be 1, the 'And-2' output has to be 1, and for that Or-1 output...
  6. Haorong Wu

    [Quantum Computing] Verify a circuit implementing and operation

    This is an exercise from "Quantum search as a quantum simulation " in Chapter "Quantum search algorithms". The circuit is shown as the following picture. For small time interval, the effect of the operation in the problem statement could be written as ## exp \left ( -i \left | \psi \right >...
  7. M

    Magnitude of the Magnetic Field near a Circuit Inclined at an Angle

    For the front wire, I got the magnitude of the magnetic field in terms of the magnitude of the magnetic force, the current, "l," and the "theta". I am unsure how to proceed because I thought that the magnetic force is independent of any other forces. I am also just lost in general. Any help...
  8. Haorong Wu

    Circuit for the inverse quantum Fourier transform

    First, the inverse quantum Fourier transform is ##\left | k \right > =\frac 1 {\sqrt {2^n}} \sum_{j=0}^{2^n-1} e^{-2 \pi ijk / 2^n} \left | j \right >##, and it is equal to ##\left | k_1 , k_2 , \dots , k_n \right > \rightarrow \frac { \left ( \left | 0 \right > + e^{-2 \pi i 0.k_n} \left...
  9. M

    Electric field in a circuit with a DC source

    So I understand that when an electric field is produced in a conductor of length L, the net electric field in the conductor will be 0 because the rearrangement of electrons in the conductor results in the production of its own electric field which cancels out the one produced initially...
  10. F

    Use a MATLAB Workspace to get the unknown values in an AC circuit

    The plot of part b is attached below. I got a warning on part a , I don't know where is my mistake . Please check my work . Part A clc; clear all; %parta f=800; t=0:10e-6:0.005; xc=10^(-6); xl=40e-3; for i=1:(0.005)/(10e-6) w=2*f*pi; zeq=xl*j*w+50; is(i)=2*(1600*t(i)*pi)...
  11. F

    Engineering Draw the magnitude and phase angle of a voltage in this AC circuit

    My solution is attached below. I am not sure if my answer is correct or not , I want to confirm it.
  12. M

    2-Resistor, 2-Capacitor Circuit with Switch

    I already did part a and got the correct answer of 4.8 microC. However, I am unsure how to approach part b, where the switch is closed and apparently the two capacitors end up with different charges. For part b, since there is a path between the two capacitors, I don't know if I am able to...
  13. A

    Engineering Need help with a linear circuit problem

    Attached is my work for the voltages, and the problem itself.
  14. Simpcar

    Discharge in a DC RC circuit and negative sign of current

    Hi everyone! I'm trying to understand why when writing the differential equation of a discharging RC circuit V_C-Ri(t)=0 \to q(t)/C - Ri(t)=0 we replace i(t) with -\frac{dq(t)}{dt}. I read many threads but I don't understand the physics behind this. The usual answers I read are something like...
  15. A

    Engineering Need help with a nonlinear circuit problem

    Hello, I have been working for hours on this single problem, to no avail. I am supposed to find the Thevenin equivalent for Voltage and Resistance, which I found to be 1ohm for resistance, and for question 2, Vth is -3V, and for 3 and 4, Vth is 1V. Any help is appreciated, as I have no clue...
  16. Z

    Find the functions of V1, V2, V3 in an RC circuit

    I tried using Kirchhof's current law, and to pose the problem in matrix form as ##\frac{dv}{dt}=Mv## with## v## the vector of the ##3## potentials at nodes ##1, 2## and ##3##, and ##M## is a ##3x3## matrix. it would be enough to show me which will be the differential equations, I would proceed...
  17. C

    What will the phasor diagram of this LCR circuit looks like?

    I know the current of capacitor and inductor must be parallel but pointing in opposite direction due to the fact they are connected in parallel thus having same voltage (please see attached screenshots). The current of resistor will simply be the sum of these two vectors, but what about its...
  18. J

    Engineering Input and Output Impedance of an Opamp Circuit

    I know for ideal opamp the input Z is infinite, and output Z is 0, but not sure about this opamp.
  19. Eugene567

    What forces are acting on electron in a circuit?

    What forces are acting on electron in a circuit? What is the source of such kind of forces? Do electrons act on each other in electric current? If i have an ordinary electric circuit with only one resistor, then if i raise resistance, the electric current goes down. As I understand it happens...
  20. Peter Alexander

    Engineering Compute the voltage gain of this bipolar junction transistor circuit

    This is the given schematic. The result should be $$A_u = \frac{R_b g_{21}}{1 + R_b g_{22}} = -50$$ and the way I wanted to tackle this problem is by stating $$A_u = \frac{-R_b i_2}{u_1} = \frac{-R_b (g_{21} u_1 + g_{22} u_2)}{u_1} = \frac{-R_b (g_{21} u_1 + g_{22} u_2)}{g_{11} u_1 + g_{12} u_2}...
  21. J

    Engineering Voltage across the output resistor for this opamp circuit

    Here is question: Find voltage across R3 options: 10V 11V 5V 2V Attempt: No current flows through Opamp, so 1mA flows through R3, this gives voltage across R3 = 1ma * 1K = 1V. But that is not in option. Where am I wrong? No current flows inside or outside opamp, right?
  22. M

    Does Mutual Inductance Affect Voltage in an Open Circuit?

    Hi, so my question is basically: Does the mutual inductance from coil 1 show up in the voltage of coil 2 even if coil 2 is an open circuit? I would think that the answer is yes, as the Mutual inductance depends on the current passing through coil 1? However, the answer scheme seems to ignore...
  23. K

    How does circuit complete when using live wire tester?

    I raise this question because at a fundamental level I still do not understand how a Capacitor works and how a circuit completes thru capacitor. The live electric tester screwdriver uses stray body capacitance to lit a neon when one end comes in contact with live wire and another with a human...
  24. runningman19

    Design of an Op Amp Circuit for Voltage Amplification

    Hi Everyone, I would like to measure voltage output from a sensor via an Arduino. The sensor outputs 20 mV at max capacity. I'd like to bump this up to around 5 volts so it is easier to measure. My plan was to use a non-inverting topology coupled with an LM393N op-amp. The schematic for a...
  25. M

    What is the Relationship Between Veb and Ie in a PNP Transistor?

    The problem: My attempt:
  26. Vantom

    How to calculate Resistors in a circuit ?

    here is the question below with all the possible answers, if anyone can help it would be appreciated
  27. Pierson5

    Complex impedance and phase angle of a circuit

    I've attached my work below. The numbers seem odd to me though. Are my equations correct? Is the phase angle really (0/12)? If so, what are the implications of that?
  28. E

    Draw an electric circuit potential graph

    Hi. I have physics homework that I don't understand. Hopefully, someone here can give me some advice. So, the homework goes like this: Draw an electric circuit potential graph and find out the potential difference between points B and C. The two resistors have equal values. Believe me or...
  29. khalil977

    Do I Need Freewheel Diodes for My H Bridge Mosfet Inverter Circuit?

    i am designing H bridbe mosfet inverter with gate driver HCPL3120 i need help in circuit
  30. W

    Engineering Identifying the purpose of a circuit from the VHDL definition file

    I have attempted to sketch the timing and got the following graph From reading the VHDL code my understanding is io each rising edge clock tick the system will carry out one of the following (choosing based on priority): reset if Clear_L is high load in a value if Clear_D is high UP count if...
  31. PaxFinnica96

    Calculating the Gauge of a Copper Wire for a Thermometer Bridge Circuit

    Hi All, Really struggling to get my head around what I'm doing wrong - every time my answer of wire diameter comes out too small for what's included in the table of SWG. I must be doing something wrong somewhere - my attempt is below. Any help is very much appreciated.
  32. preet_jay

    Circuit Analysis Question -- Solving for a multi-resistor circuit

    From what I understand is that you can sum up R3 and R4 to get 350 ohms Then you can can a parallel circuit with the missing resistors, 4amp and the new 350 ohm resistor and that's about it. My textbook says the answer is 55 ohms for the resistors and the current is 0.073 but I got 3.75 ohms...
  33. C

    Engineering Can this circuit be simplified any further?

    I have simplified it at first by giving and equivalent resistance to resistors in parallel on the right and also equivalent in series resistance at the start. Would 16v-7v be the correct way of equalizing the voltage by using Kirchhoff's voltage law?
  34. DeclanKerr

    RLC Circuit Analysis with system of ODEs

    Summary: Looking for guidance on how to model an RLC circuit with a system of ODES, where the variables are the resistor and inductor voltages. This is a maths problem I have to complete for homework. The problem is trying to prove that the attached circuit diagram can be modeled using the...
  35. BluJay214

    Circuit confusion, light bulbs, switches, and batteries

    Before I modeled it, I thought the current would move in a figure 8 due to the battery on the right still loading the current. Then I thought of how the battery on the left would counteract that current. I am still not sure what is going on here. Is it kind of like a short circuit where the...
  36. L

    Parallel Equipment Grounding Conductors, Short Circuit

    I am seeking direction, information, resources and thoughts on the following subject. The common interpretation of the National Electrical Code does not allow you to use multiple smaller equipment grounding conductors in place of one larger one (except in a few cases such as a cable assembly...
  37. QuantumRose

    Kirchhoff's rule for circuit with two batteries

  38. B

    How Do You Find Current and Voltage for Resistors with 4V, 8V, and 12V Supply?

  39. paulmdrdo

    Engineering Does Zero Initial Energy Affect the Rate of Change in 2nd Order Op-Amp Outputs?

    I was reading about this 2nd order op-amp circuit which is essentially a cascaded integrator and got confused with the explanation of the book regarding the rate of change of the outputs. The book said that when the initial energy stored in the circuit is zero then this rate of change is zero...
  40. M

    𝑗 - 𝜔 method alternating current circuit help

    I'm supposed to calculate the current and the phase angle. Can someone please tell me if this is the correct solution?
  41. Electgineer

    Find the power supplied by the 1V source in the circuit using nodal analysis

    My attempt: At node 1 > 4 = 6 + I1 Node 2 > I1 + I2 = I 2 Node 3 > 6 = I 3 + I 4 I1 = (V1 - 4)/21 In node 1, Using the equation for I1, V1 = -38V. I2 = (V1 - 4 - 1)/2 So, I2 = -21.5APower supplied by the 1V battery is P=VI P=-21.5 x 1 P=-21.5W I am not sure of my method, I just started...
  42. J

    Detecting metals with a capacitance multimeter and a circuit

    A makeshift metal detector can be made if you have an accurate INDUCTANCE meter and a coil of a large diameter. Instead, I've got a capacitance meter, this one: http://www.pw-electronics.co.uk/DMM.pdf How can a little circuit be added (like a capacitor with a resistor in series or in parallel...
  43. christang_1023

    LR Circuit Analysis: Solving Equations w/ Kirchhoff's Rule

    Above is the figure of the question. According to Kirchhoff's Rule, I have obtained three equations $$\varepsilon-iR_{10}-L_{40}\frac{di_1}{dt}=0$$ $$L_{40}\frac{di_1}{dt}-i_2R_{60}=0$$ $$i_2R_{60}-R_{30}(i-i_1-i_2)-L_{15}\frac{d(i-i_1-i_2)}{dt}=0,$$ where ##\varepsilon## stands for emf=100V...
  44. cianfa72

    Galvanic cell - open circuit voltage and EMF

    Hi, having not a deep knowledge of electrochemistry I've some doubts about processes involved in a galvanic cell. Take for instance a Zn/Cu Daniell cell for which E0cell is 1,10V. That means emf for it is 1,10V. Starting to read from how battery works I had a first understanding of how...
  45. T

    Using a generator to charge 2 batteries

    My project is to create a circuit for a stroller that can store the mechanical work into electrical while moving around and with the push of a switch, use the electrically stored energy to assist the movement of the stroller. I’ve tried capacitors but it ended up not being enough voltage and I...
  46. M

    Circuit Transformations: Norton's Theorem

    Picture of the circuit is posted below. Apologies, the voltage source on the left should read 24 V. My question is: What is wrong with this method? [Edit: Sorry if it wasn't clear- the method in the picture yields the wrong answer] When I originally did the question, I just turned the LHS into...
  47. Electgineer

    Is there a better way to assign current direction in circuit analysis?

    Is there like a rule of thumb, or a simple hack for assigning current direction in circuit analysis? Even when I m consistent with the direction I choose, I still get the wrong answer most of the time. Like 1. Do current source or voltage source affect when choosing current direction? 2...
  48. Salman Ali

    Question about a Flip Flop circuit

    Hello! I am confused in a question I found on youtube. I have uploaded the screen shots. He told that with respect to S and R we have to write the change from Q to Q+( next state). But I am not getting it. How he wrote Q+ states?Is he considering that when S=1 , we have to set the circuit i.e on...
  49. paulmdrdo

    Engineering Graphing the response of an underdamped circuit

    I'm having difficulty as to how I would produce an approximately graph of the response just by hand. I was able to determine the first maximum by taking the derivative of the response and setting to zero and I'm stuck. How do I know the succeding minimum and maximum of this response? TIA.
  50. paulmdrdo

    Engineering How were tangent terms derived in solving for eqn (2) in a second-order circuit?

    I was trying to follow the solution for this problem and got stuck in the last portion of the solution. I encircled the part that I did not understand. I can't figure out how the solver was able to come up with tangent terms. Please enlighten me. TIA
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