What is Circuit: Definition and 1000 Discussions

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. W

    How to find the current and voltage in a circuit with current sources?

    Summary: Facing a circuit with 2 parallel resistors and 2 current sources (1 dependent, 1 independent). Trying to find the current, voltage, power delivered by the independent current source and power delivered by the dependent current source. I'm trying to start by finding the current i0 but...
  2. U

    Very basic circuit question about a Wheatstone Bridge

    I tried to solve by making 4 ohm and 8 ohm, which I believe are parallel as one effective resistance, and making 6 and 12 ohms which I believe are parallel as one effective resistance, and diving the total of the two effective resistance by the total voltage, but by doing so, I can only find...
  3. U

    Circuit Q Basics: Understand Electrical Circuits

  4. M

    Engineering Determine if the dependent source of the circuit delivering power or....

    Hi all ! I want a confirmation for this exercise please. The circuit: This is my try: https://www.docdroid.net/EFuTDMp/new-doc-2019-10-03-234340-1-converted.pdf -- Thanks
  5. ethanh100

    Help with Circuit Nodal Analysis

    Summary: Perform nodal analysis on a circuit to find voltages. For a laboratory I am trying to find the nodal voltages for a circuit we built using hand calculations. I have the answer as we ran the simulation which shows all the nodal voltages, however my nodal analysis seems to be wrong as I...
  6. D

    Parallel circuit with internal resistance

    4 resistors R1= 10 Ohm R2= 7 Ohm R3= 6 Ohm R4 = 18 Ohm, internal resistance of source is 0,5 Ohm and supply voltage is 27V Total resistance in parallel resistors 1/R = 0.465 taking the inverse of that i get 2,15 Ohm. Add to that the internal 0,5 and the total comes out to 2,65 Ohm. Total...
  7. S

    Solving Power Delivery Issues in a 5V Series Circuit with a 1.5V Rated Relay

    Hello, I'm using a "TQ2SA-1.5V Panasonic 2 Form C AS Single side stable, 1.5VDC 2A DPDT NON-LATCHING SMD Relay" (specifically the coil side of this relay) that is rated for 1.5 volts that is connected in series to this circuit (as the last device in this circuit shown below), which in this...
  8. F

    Engineering Determine the shunt field current in a magnetic circuit

    Problem Statement : Here's my attempt : * By assuming that the fringing and leakage effects are ignored. I find the flux density , the permeability and the reluctance of the iron , but then I get stuck . Any help would be greatly appreciated .
  9. E

    Is the current through the electrolyte double that through the circuit?

    Suppose, just for explanation purposes, we have an electrolyte of Na+ and Cl- ions connected to an external circuit with an ammeter which reads 96500A. In 1 second, we expect 96500C of charge to flow out of the cathode as 1 mole of Na+ ions are reduced, and the same amount of charge to flow...
  10. M

    Engineering Transient circuit analysis problem with a dependent source

    Hi all, I tried to solve this, but I can't find the R(equal). I use the following method. The circuit: For t<0 the switch is closed so the iL(0-)=4 A For t>0 it opens and the iL(∞)=0 A Now, I want to find the value τ=L/R(equal) Then I will use the: iL(t) = iL(∞) + ( iL(0-) - iL(∞) )* (...
  11. mpulis

    Electrical Increasing current in an intercom circuit

    Hi, I have purchased an electric lock some months ago. Now I purchased an intercom system which is rated at 1.2Amps. The cabling is rated at 1Amp. The lock is working sporadically. I guess it is because of the current. Is it possible that I boost the current received? Maybe through a relay? So...
  12. M

    Calculating Vo in an AC Circuit Using Superposition Theorem

    This is the circuit: I try with KVL: But the given answer is 6.66L33.67 Volts. So, I'm confused, any suggestions ?
  13. S

    Q of R+LC Circuit: Understanding Q & Phasor Analysis

    I've been experimenting with an LC tank circuit in series with a resistance R, and I've noted that the Q seems to increase with R. I've tried to derive this result via phasor analysis, but I'm not sure if my expression is correct. To make things clear, I'm talking about the circuit with...
  14. J

    Finding the thickness of graphite in a circuit

    Summary: I have tried everything to understand this but I cant. Please help me. In class, I "drew a circuit" with a pencil. When the LED was moderately bright about 9mA was flowing and so (since I was using a 9V battery), the resistance was about 1 kΩΩ. At this point, the distance 𝐿L between...
  15. brainbaby

    Determine the output impedance of the circuit

    Hi friends, I have taken three sine AC sources and have joined them in series. I want to find the output impedance of this circuit. Formula that I am using is...Output impedance = (Open circuit voltage - Output voltage with load R1) / Output current with load (R1) Load resistance = 1 k ohm...
  16. Physics lover

    Maximum power in this resistor circuit

    My attempt-: So the resistance is coming to be negative.Can anyone tell me my mistake.Thanks.
  17. M

    Calculating Component Values in this Low-Frequency CE Amplifier Circuit

    Hi guys , i need help. How do i calculate C1? fu=25Hz
  18. M

    Calculating R1 and R2 for Opto-Triac Output Circuit

    Homework Statement: Referring to the opto-triac output circuit shown below. ... Given the following parameters: Logic voltage = 3.3 V D1 forward voltage drop = 1.8 V D1 operating current = 10 mA Opto-triac minimum operating current = 2 mA Opto-triac LED forward voltage drop = 1.6V Calculate...
  19. C

    Voltage received by each bulb in a circuit

    Summary: Voltage received by each bulb in a circuit How much Voltage does each bulb receive in the diagram below? (In terms of 1v being the voltage supplied by each cell)
  20. W

    Theoretical question about an electromagnet in an AC circuit

    This may be a stupid question, but here is what I am asking. Using a very simple circuit, say 120v AC water heating element rated at 1000 watts meaning 120v AC hot leg on 1 terminal and a neutral on the other terminal. That would give 8.3 amps of current, meaning the resistance would be 14.4...
  21. EDCJZ

    Can You Solve This Capacitor Circuit Problem Using Q=CV?

    Homework Statement: Help me please Homework Equations: Q=CV
  22. Zahid Iftikhar

    Voltage across R, L and C vs AC Voltage source in RLC Series Circuit

    One property of series resonance circuit is that at resonance, the voltage across circuit elements R,L and C may be larger than the source voltage. I can relate it to vector analogy where component vectors may have larger values than the resultant and the phenomenon is counter-intuitive. This...
  23. A

    How can I calculate the equivalent resistance of this circuit?

    i was trying to calculate equivalent resistance of this circuit and that was my attempt : 1) i can see two parallel 20 ohm resistors so equivalent resistance = $${20 \over 2} = 10 ohm$$ 2) now we are left with 20 ohm resistor and 10 ohm resistor which are connected in series so equivalent...
  24. A

    Trying to get equivalent resistance of a circuit

    i had a problem in my textbook asking me to get equivalent resistance of a circuit , i ended up getting 23.7 ohm as my answer but my textbook says that the correct answer is 100 ohm you can see my attempt here : imgur link : i really want to know what went wrong with my steps thanks in advance
  25. L

    Circuit analysis: Six resistors and two batteries

    Problem Statement: ) A circuit is constructed with six resistors and two ideal batteries as shown. The battery emfs are ε1 = 18 V and ε2 = 12 V. The values for the resistors are: R1 = R5 = 55 Ω, R2 = R6 = 110 Ω, R3 = 44 Ω, and R4 = 117 Ω. The chosen positive directions for the currents are...
  26. wirefree

    Engineering Diode circuit with a Capacitor

    Summary: Seek help with the working of a Capacitor in the presence of a DC & AC voltage source. I greatly appreciate this opportunity to submit a question. It's a homework problem and I only seek to clear my concepts. Problem: Find amplitude of the ripple voltage across the resistor...
  27. JamesBennettBeta

    Finding the Open Circuit Voltage

    Problem Statement: While KLM points remain connected, the connection between points XY is removed. Calculate the potential difference between points XY in this situation. Relevant Equations: V=IR, KVL
  28. S

    Set up the differential equation showing the voltage V(t) for this RC circuit

    Hi all. I have another exam question that I am not so sure about. I've solved similar problems in textbooks but I have a feeling once again that the correct way to solve this problem is much simpler and eluding me. Especially because my answer to a) is already the solution to c) and d) (I did...
  29. felipe_damascena

    Engineering Create a Sine Wave Circuit Design for Inverting Voltage | Step-by-Step Guide

    Summary: I want to design an electronic circuit that takes an sine wave as input and output a different wave I want to design an electronic circuit that takes a sine wave as input(Vi) and it outputs a different wave (Vo). Vi goes from +5V to -5V Vo is constant with the value of three, when Vi...
  30. X

    Why can we ignore certain circuit paths?

    I get really confused with these types of problems. I don't know how to break down the circuit properly. I tried to go anticlockwise and ignored the ammeter and the voltmeter as circuit components, which gave me R1 and R2 in series while R3 and R5 (in series) are in parallel with R4 and R6 (also...
  31. jisbon

    Checking My Understanding of a Magnetic Circuit: Help Appreciated!

    So I was checking this question out, and I saw that someone did discuss about a similar question before on this forum here: https://www.physicsforums.com/threads/did-i-get-it-right-by-coincidence.487088/ Since this is a different question, I would like to ask if anyone here could help me check...
  32. D

    50Hz 3 Phase Circuit - Twisting to reduce EMI?

    I have done the maths to work out the Induced Voltage on a communication cable, from a bunch of 3 phase circuits in a panel - with the minimum distance between them I calculated it to be about 1.5nV; but for a larger system where there could be larger loads on the cables I was thinking about...
  33. 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...
  34. 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
  35. 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...
  36. 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...
  37. 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...
  38. 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 >...
  39. 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...
  40. 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...
  41. 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...
  42. 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)...
  43. 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.
  44. 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...
  45. A

    Engineering Need help with a linear circuit problem

    Attached is my work for the voltages, and the problem itself.
  46. 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...
  47. 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...
  48. 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...
  49. 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...
  50. 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.
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