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. FreeForAll

    Solving a Perplexing Thought Experiment: A DC Electrical Circuit

    This thought experiment has been bugging me for a very long time - I'm hoping someone can help me understand it. Premise: - Simple DC electrical circuit consisting of a battery, wire, light bulb, and another wire to complete the circuit. - Each wire has a length of 1 light-year (yes, very...
  2. bornofflame

    RC circuit - Rate o'energy dissipated = rate o'energy stored

    Homework Statement 1. A 2.01 uFcapacitor that is initially uncharged is connected in series with a 6.51 kΩ resistor and an emf source with 74.6 V and negligible internal resistance. The circuit is completed at t = 0. b) At what value of t is the rate at which electrical energy is being...
  3. Kevin J

    Confusion about this Live & Neutral Circuit Problem

    The left circuit is a simple live&neutral circuit, it is neutral (0V), because it is in fact 'grounded'. If I unplug the wire connection to the ground, makes both wire, live. Now, If I replace the grounding connection with a person, why would he receive the shock, doesn't the man 'neutralize'...
  4. bornofflame

    RC Circuit - Rate energy is dissipated in the resistor

    Homework Statement 1. A 2.01 uFcapacitor that is initially uncharged is connected in series with a 6.51 kΩ resistor and an emf source with 74.6 V and negligible internal resistance. The circuit is completed at t = 0. a) Just after the circuit is completed, what is the rate at which electrical...
  5. Krushnaraj Pandya

    EMF and potential in a circuit

    Homework Statement Four identical cells each having emf E and internal resistance r are connected in series to form a loop abcd as shown in figure (picture 1). Find potential difference across ab and ac. 2. Homework Equations V=IR equations for combination of cells and resistances The...
  6. W

    Engineering Grounding Op-Amp circuit exercise

    Homework Statement 2. Homework Equations 3. The Attempt at a Solution For the first set of questions: I've worked through to part 6), at which is I encountered my first problem. I'm not entirely sure what the question is asking. Is it as if there would be a capacitor between...
  7. Kevin J

    B Is it Possible for a Short Circuit to Contradict Voltage in a Parallel Circuit?

    Assume a superconducting parallel circuit being shorted, a 10V ideal battery, and a 5 Ohms resistor connected on one of its path. This means the shorted path has a 0 Ohm resistance, which also means it has no potential difference, how is this even possible if voltage across in a parallel circuit...
  8. S

    Current through circuit when switch is open

    Homework Statement Seven equal resistors, each of resistance 2Ω are connected with a battery of 3V in a circuit shown. If i1 is the current when the switch S is open and i2 is the current when switch S is closed, find the value of i1/i2. Homework Equations 1)Equivalent resistance formula...
  9. Kevin J

    Why does current choose the short circuit path?

    I've seen answers saying that electricity takes path of least resistance, I know this and there is no need to explain this for me. A forum's answer told me that the electrons initially flow through to the path with resistance and eventually becomes congested (redirecting the remaining electrons...
  10. D

    Did I count this current in a circuit correctly?

    This i a test question and we are not allowed to use a calculator, so I was wondering whether I did everything correctly, since the I1 = - 1/7. I am supposed to find out I3, but stopped at I1, since the result is a bit tricky. 1. Homework Statement R1 = 10 ohm, R2 = 20 ohm, R3 = 40 ohm I3 = ...
  11. O

    Comparing the brightness of each bulb in a circuit

    Homework Statement Four identical light bulbs are connected to a battery as shown in the diagram. Switch S is originally closed. If switch S is opened, what happens to the brightness of each bulb? Homework Equations V=IR The Attempt at a Solution - By opening the switch, no more current...
  12. Shivang kohlii

    Engineering An electric bulb of 500 W at 100v is used in a circuit

    If the circuit has 200 V supply. The resistance R that must be put in series with bulb so that it draws 500 w is? 2. Relevent equations P= v^2/r I = v/r 3. My attempt at the solution R= V^2/P r (bulb)= 10000/500 = 20 ohm Now for 200 v supply .. P= 500 W V= 200V Rnet = 20 + R R+20= 80 R= 60...
  13. P

    Why does switching this circuit on take longer

    Homework Statement In this circuit, switching on is about twice as long as the delay for switching off 2. Homework Equations 3. The Attempt at a Solution When switching this circuit on the inductor will oppose the change of current therefore basically slow down the lighting of bulb B. When...
  14. CMJ96

    A Help Understanding a Quantum Circuit Identity

    Hello I have the following quantum circuit identity for converting a controlled U gate (4x4 matrix) into a series of CNOT gates and single qubit gates $$ U= AXA^{\dagger}X$$ where A is a unitary matrix. Here is a picture of the mentioned identity. Can someone help me understand conceptually...
  15. J

    Circuit with resistor, switch and capacitor

    Homework Statement We have a circuit with a battery, two resistors, a switch and a capacitor. We assume that the battery has a switch so that we can choose whether it should be a voltage source for the circuit. a) At time t = 0, we put on a voltage Vs over the battery in the circuit. What is...
  16. S

    Engineering Solve LC Circuit Problem: Examples & Resources

    Homework Statement An image of the problem is attached. I have to find 2 currents in an LC circuit. Homework Equations V = L(di/dt) The Attempt at a Solution [/B] I have no clue how to do this type of problem. Are there any examples problems similar to this online? Or can someone give me...
  17. F

    Engineering Write the Boolean expression of a given logic circuit

    Homework Statement In the logic circuit shown below , write the Boolean expression for the output function X . Which gate(s) could be removed without affecting the function X ? Homework Equations - The Attempt at a Solution [/B] So , we can get rid of ##A \overline{B} C ## . gate # 4. Right ?
  18. Muhammad Usman

    Pull Up resistor in the Voltage?

    Hi, May be this is the most basic question, but I don't understand the concept of pull up resistor and how they maintain the voltage value. For example let's take an example of below circuit. There is 5 volts battery and then there is 10K resistor which is further connected with the Vout which...
  19. S

    Engineering Op-Amp Resistive Circuit Homework: Finding Vo in a Given Circuit

    Homework Statement The attached picture is the circuit I have been given and I am asked to find Vo (the voltage drop across the 6k resistor. Homework Equations v_out/v_in = (R_1 + R_2)/R_1 V+ = V- The Attempt at a Solution So I know that the voltage drop across the 6k resistor is just the...
  20. C

    Symmetry in Electrical Circuit Analysis

    How is symmetry used to solve electrical circuits? I have seen several problems in books in which currents in two resistors are said to be equal due to 'symmetry'. That is a concept that I fail to understand and thus cannot apply. In class, we were shown a few circuit diagrams which were...
  21. E

    Dispersion equation for an LC Circuit

    Need the dispersion equation for chain consisting of cell units ( LC unit scheme in attachments). I know I need to make complex Kirchhoff equations and after get the dispersion equation but absolutely don't know how to do it. All examples that I find in web very poor including books, articles...
  22. Shaq Melbourne

    Engineering LabVIEW Opamp Circuit Homework Solution with USB6008 Measurements

    Homework Statement The task States to build the I-V characteristic circuit where AIa and AIb are floating source measurements taken with the USB6008 and VS is supplied by the voltage follower circuit. I've also attached the actual script, for added context. Homework EquationsThe Attempt at a...
  23. S

    Equivalent circuit of the waveguide application problem

    Hello! I'm trying to simulate a connection between two 2-port devices via waveguide but calculated results do not agree with those, calculated in simulation software. All calculations are in the notebooks. I took a two-port device and compared its S11 characteristic calculated using equivalent...
  24. A

    Combination Circuit Help (pic)

    Could somebody help me out with this combination circuit? The answer that I get is 62K but that is not one of the answers. At first, I thought the 10kohm and 20kohm wherein series and the other side as well. Then I thought they are all in parallel because of the different current flow they all...
  25. Safder Aree

    Engineering Finding Internal Resistance through Circuit Analysis

    Homework Statement Given this following circuit: What is the internal resistance of the meter movement ( R_I). This is part of a project I'm doing and I know the equation that gives you the internal resistance in this circuit. $$R_I = \frac{R_sR_p}{R_s - R_p}$$. However, I have no idea how...
  26. Lapse

    Engineering Design Circuit to Convert Current to Voltage | LTSpice Also

    Hello, We just finished up midterms and I actually did well--got an A. However, somehow between the midterm (class before last) and last class we jumped to creating a circuit with a diode. I am pretty lost. 1. Homework Statement Homework Equations Voltage / Current = ResistanceThe Attempt...
  27. cnh1995

    Transient in a coupled circuit

    Homework Statement Homework Equations Kirchhoff's lawsThe Attempt at a Solution Applying KVL on primary, di1/dt+i1=5+2di2/dt...1) Similarly for secondary, 2di1/dt= 4di2/dt + i2...2) After solving these equations using Laplace Transform, I got I1= 5-e-0.2t A and I2 = 2e-0.2t-2e-0.25t. I...
  28. M

    Hi, how to make 2 IF from one IF amplifier circuit, to get higher gain

    Hi, i take one If amplifier, from internet and i want to make the second the same, but i don't know how to couple, of what i need to do, to get more gaing can somebody help me? here is one IF amplifier in ltspice, rename in asc, or remove only txt extesion. and what is the best to do, is for fm...
  29. G

    Explaining a signal converting circuit

    i have a drawing of a circuit that converts a signal in range [-5,5] V to a range [0,1.2]V . i wish to understand how it works.. i have basic knowledge of electricity as an undergraduate in general physics but a bit rusty , thus i am here looking for answers...
  30. Y

    State Space Model of an RL Circuit

    Homework Statement For the given circuits, identify state variables and derive a state-space model for each. Assume the input is v(t) and the output is vL(t). Homework EquationsThe Attempt at a Solution [/B] So my issue is that I solved this problem using two different methods. First...
  31. K

    Tripping Behavior of Circuit Breakers

    For US residents. If you have the above circuit breaker put in your panel phase to phase (2 pole).. and one of the phase touches neutral.. would the circuit breaker trip or not? It's rated 240 volts.. yet one pole only has 120 volts.. would that 120 volts shorting the neutral trips it? This...
  32. ItsTheSebbe

    Finding the bandwidth of a parallel RLC circuit (+MATLAB)

    Homework Statement The attempt at a solution Constructing the total impedance of the circuit as follows, $$\frac{1}{Z_T}=\frac{1}{Z_R}+\frac{1}{Z_C}+\frac{1}{Z_L}$$ where $Z_R=R$, $Z_C=-j\frac{1}{\omega C}$ and $Z_L=j\omega L$. $$\frac{1}{Z_T}=\frac{1}{R}+j\omega C+\frac{1}{j\omega L}$$...
  33. Casper Hansen

    Thevenin equivalent (symbolic circuit calculation)

    Homework Statement I have trouble to find the right procedure to transform the circuit below to a thevenin equivalent. I am looking for a symbolic solution a step by step guidance of where to start and how to add/locate all the impedance in series and parallel in order to calculate the sum of Z...
  34. Lapse

    Engineering Question About A Particular Circuit in LTSpice

    I am simply attempting to design a circuit in LTSpice. We just started on dependent sources. I am having trouble designing this guy here: Here's what I've got: What does this error mean? What do I need to change to make this circuit work?
  35. prashantakerkar

    Smartphones with inbuilt projector circuit

    Is it feasible to design and construct State of the art Smartphones with inbuilt mini projector device functionality ? As we know there is a inbuilt torch feature in the Smartphones but has limited functionality. If not, Why? Thanks & Regards, Prashant S Akerkar
  36. O

    How to fix this electric circuit

    Homework Statement I'm not sure if the construction of this circuit is correct, so that both lamps, which are the same, shine equally brightly. Otherwise only the resistors are given. If it's wrong, what else would it look like? And why?[/B] Homework Equations I guess the laws of Kirchoff...
  37. cnh1995

    H-field and MMF in a magnetic circuit

    I have been revising magnetic circuits concepts and I think I am missing something regarding H-field and mmf. If the 100-turn primary of a transformer is energized with 1A dc, its mmf will be 100A-T. And all the line integrals H.dl enclosing the primary coil will equal 100A. As per magnetic...
  38. AchillesWrathfulLove

    Which is more accurate when analyzing a circuit (for V, I or R)

    When analyzing a circuit which is more accurate: Using hand calculations, software calculations or using multi-meter. Which one should be relied upon the first?
  39. J

    Which circuit shows the correct connection and values?

    Homework Statement Question: For the circuits shown in Fig. 6, voltage meters and ampere meters are used to measure the voltage across the load and their current flow. If the Red Probe is plugged into the “+” terminal of the voltage meter and ampere meter, which circuit(s) show both the...
  40. AchillesWrathfulLove

    When using the Superposition method to solve a circuit....

    do you eliminate an independent current/voltage source one at a time or can you do all of them at once. Let us say you have 5 independent voltage sources and 5 independent current sources. Do you short circuit 5 of those voltage sources and leave 5 independent current sources or do you have to...
  41. P

    Engineering Solve this Circuit using both Nodal Analysis and Mesh Analysis

    Homework Statement [/B] Determine, Using the values given in TABLE A, the current I in the circuit of figure 2 by (a) Mesh analysis (b) Nodal analysis Circuit diagram and given variable attached. V1 = 120 V2 = j120 V3 = 14.142+j14.142 Z1= 2 Z2=-J5 Z3=4 Z4=-J5 Z5=J4Homework Equations [/B] KVL...
  42. AchillesWrathfulLove

    Engineering Do electrical engineers actually use Circuit Analysis skills?

    Do electrical engineers actually use stuff that is taught in Circuit Analysis classes like Node Voltage Method, Mesh Current Method, Kirchhoff Voltage/Current Law, Source Transformation. All these usually only involve resistors. Are they somewhat altered in a way to analyze circuits with other...
  43. AchillesWrathfulLove

    Which is a better method for Circuit Analysis?

    Node Voltage Method or Mesh Current Method.
  44. Islam Sabry

    The equivalent resistance for the resistors in this circuit?

    Homework Statement If the circuit of parallel and series resistors , is as follows , what's the equivalent resistance for the group? Homework Equations neglecting the battery internal resistance... irrelevant to the question. The Attempt at a Solution I tried to do the following R1=8+12=20...
  45. E

    Pulsating DC supply to LC circuit

    I have a very basic question for the professionals here, but I am having a small issue with my parallel LC circuit. I have an inductor that is 6.425mH, a capacitor that is 217uF (it is two 470uF aluminum electrolytic caps connected in series to make one non-polar 217uF cap). I am supplying the...
  46. H

    Why is the potential drop in the wire not considered in a circuit?

    A battery induces an electric field throughout a circuit in such a way that the electric field exists in the wire and the resistance. By moving in the direction of electric field, we expect that the potential decreases no matter we move in the wire or in the resistance. However, we only consider...
  47. S

    I Sign of the terms in a circuit

    Hello! I am a bit confused about the sign of the ##L\frac{dI}{dt}## term in the circuits (DC circuits). In my book it is defined with a minus, on wikipedia it is defined with a plus and I am not sure which one should I use. I can pick any sign I want and the result will come out right...
  48. J

    Engineering AC Source driving an RLC circuit....

    Homework Statement 10 v, 100 hz goes into a circuit of a 1o resistor, a 1o inductive reactance and a 1o capacitive reactance that are in series. What is the current. What is the V across the cap. Homework Equations and the attempt at a solution[/B] So I know I = V/Z and Z = sqrt( R^2 +...
  49. Curiosity 1

    Engineering Three-phase circuit: Why Z_Ye is parallel with Z_Δ?

    Homework Statement This problem is taken from Fundamentals of Electric Circuits (chapter 12, problem 15). Homework Equations As shown in the first blue box, I have trouble seeing why after the conversion, Z_Ye will be parallel with Z_Y. I think it's because the voltages 'emitting' from the...
  50. J

    A one light-year circuit of christmas lights

    I have a bit of a puzzle I'm trying to answer. A K2 civ decides to celebrate Christmas, so they build a circuit of trillions of Christmas lights 1 LY in circumference. When they flip the on switch, what happens? Do the lights come turn on one after the other in response to the electrical...
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