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. 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...
  2. 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?
  3. 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
  4. 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...
  5. 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...
  6. 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?
  7. 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...
  8. 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...
  9. 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...
  10. 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...
  11. AchillesWrathfulLove

    Which is a better method for Circuit Analysis?

    Node Voltage Method or Mesh Current Method.
  12. 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...
  13. 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...
  14. 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...
  15. 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...
  16. 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 +...
  17. 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...
  18. 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...
  19. J

    RL Circuit Refresher: Solve Total Current

    Hi, I have just been refreshing my theory and was going over a parallel RL circuit, like this one. The site I was reading had this for the total current I tried some values as a test but it doesn't give me the correct answer, for total current. eg if I set V=10V R=2.5ohm jXl=5ohm Then...
  20. N

    High-Power Switching using MOSFETs

    For a project, I need a means of switching a high-current circuit between two inductors. The purpose is, each inductor serves as an electromagnet, and they are switched every 15s or so in order for one of the two to cool before starting again. The system I've designed uses arduino as a...
  21. Krushnaraj Pandya

    Analyzing a circuit with 1 point earthed

    Homework Statement Find potential of A and B in the given figure. (pardon poor quality, I only have a webcam) Homework Equations All related The Attempt at a Solution marking 1 to 4 from left to right. C1,C2,C3 are in series. C123=(2/3)C. which is in parallel with C4. C effective is 5C/3...
  22. Krushnaraj Pandya

    Analyzing a circuit with multiple batteries

    Homework Statement Find charge on 3 capacitors. Join two squares with one common side. At the middle of the common edge, place C3=6uF (micro-farad). On upper edge of left square, place C1=2uF. On upper edge of right square place C2=4uF. On lower edge of left square, a battery-10V and on lower...
  23. Krushnaraj Pandya

    Find the equivalent capacitance of the circuit

    Homework Statement Find equivalent capacitance between A and B of the given figure (pardon camera quality) Homework Equations All related The Attempt at a Solution marking junctions, From left to right, starting from original point A-and ending at B I wrote potential at them as follows...
  24. Mzzed

    RF Power Meter / SWR Meter Equivalent Circuit

    I'm starting to get into RF electronics, and an upcoming project involves the use of a power meter / SWR meter. How do we model a power meter in terms of an equivalent circuit? i.e. is it just another impedance? or a transformer? or does it not effect the circuit at all, so we just don't include...
  25. P

    Why don't voltages add up numerically in an LCR AC circuit?

    The attempt at a solution (Assuming the components are in series of this order: resistor, inductor, capacitor So I know that the phases are not in sync, that as the voltage oscillates the voltage across each component in the circuit is different. At the peak voltage aka peak current the voltage...
  26. icesalmon

    Engineering Finding the Thevenin Equivalent Circuit for a Network with a Load Resistor

    Homework Statement I just want to check to see if my understanding in anything here has gaps. Q: Find the Thevenin equivalent circuit for the network external to he load resistor ##R_L##: Homework Equations Ohm's Law: ## V = IR ## Kirchoff's Voltage Law: Σ##V_{drops}## + Σ##V_{gains}## = 0...
  27. D

    Engineering Applying Kirchoff's Voltage Law to a circuit

    Homework Statement Using Kirchhoff’s rules, (a) find the current in each resistor shown in Figure P28.31 and (b) find the potential difference between points c and f.[/B]Homework Equations [/B] Σ ΔV = 0 (KVL) The Attempt at a Solution [/B] I have been trying to set up a system of equations...
  28. F

    Basic question about current in an electric circuit

    Let's say we have a basic electric circuit consisting of a battery with some potential difference, and a loop of wire. The wire loop also has some segment with a higher resistance. Now since there is a potential difference, the free electrons will move to make the circuit equipotential. The...
  29. A

    AC circuit, voltage and frequency problem

    Homework Statement According to Equation 20.7, an ac voltage V is given as a function of time t by V = Vo sin 2ft, where Vo is the peak voltage and f is the frequency (in hertz). For a frequency of 64.7 Hz, what is the smallest value of the time at which the voltage equals one-half of the...
  30. icesalmon

    Engineering Find the Thevenin equivalent circuit

    Homework Statement Find the Thevenin equivalent circuit for the portions of the networks in the following circuit: Homework Equations Kirchoff's Voltage Law: ΣVdrops = ΣVgains Kirchoff's Current Law: ΣIclosed loop = 0 Ohms Law: V = IR The Attempt at a Solution Determination of the Thevenin...
  31. A

    Engineering Confusing circuit analysis question

    Hi I have the following situation: (Please see attached pic) I want to know if equation (4) i have written is correct. What is confusing me is that, I remember being told in circuit analysis that each energy storage element should have its own state variable. But in this situation when I...
  32. K

    I RL circuit with polynomial forcing function solution (units)

    Hello. This is the differential equation. $$ i \cdot \dfrac{R}{L} + \dfrac{di}{dt} = t $$ My solution path: Homogenous solution: $$ r + \dfrac{R}{L} = 0 \\ \\ r = -\dfrac{R}{L} \\ \\ i_{h}(t) = C_{0} e^{ -\dfrac{R}{L} t} \\ \\ $$ Particular solution: Try $$ y_{p} = at + b \\ \\ y_{p}...
  33. Santilopez10

    Circuit problem involving sources and resistors

    Homework Statement The currents ##I_{{a}}## and ##I_{{b}}## of the circuit have values 4A and -2A in that respective order. A) Find ##I_{{g}}## B) Find the power dissipated by each resistance C) Find ##V_{{g}}## (voltage drop across the current source) D) Show that the power delivered by the...
  34. Santilopez10

    Untangling a Confusing Circuit: Solving Kirchoff's DC Laws

    Homework Statement It’s a rather confusing circuit, I’m having problems trying to understand the way current circulates through the circuit. Homework Equations Kirchoff’s DC circuits laws only, no resistive simplification neither nodal analysis The Attempt at a Solution I’ll attach my intent...
  35. M

    Engineering Voltmeter and ammeter calculation in a circuit

    Homework Statement [/B] Hello, basically I have some tasks about calculating the reading of voltmeter and ammeter in a circuit, I can solve these with simpler circuits, where voltmeter is reading a few elements, but as in the ones below, I'm not sure where to begin and what to add into the...
  36. M

    Hello, I with this circuit, an RF oscillator

    Hello, Can somebody help, to understand the transistor, what does do 390pF and C(tune), and 4,3µH, they form tank circiuits? and also resistor 1K and capacitor .1, is possible somebody with little words to descirbe how it works please... Thanks.
  37. E

    Combined resistance in this circuit

    Homework Statement Find the combined resistance once the switch is closed. Homework Equations V=IR The Attempt at a Solution I tried applying Kirchoff’s law but I got many equations, I am sure there is a more efficient way. I also tried to re-draw the circuit, but wasn't sure how to do so...
  38. thee qs

    Find the resistance and EMF in a circuit

    Homework Statement translation ; we know the values of R1 = 1 ohm R2= 2 ohm R3= 6 ohm R4= 2 ohm R5= 4 ohm R6= 4 ohm we can also see the voltmeter reading a potential difference value of 8 volts , and the...
  39. MaxR2018

    Engineering RLC circuit solved with Laplace transformation

    Hi, i need some help here. Can you help me?:sorry: Here is the problem. Exercise statement: The switch have been closed for a long time y is opened at t=0. Using Laplace's transtormation calculate V0(t) for t ≥ 0 This is what i made to solve it: 1) I know while the switch is closed, the...
  40. C

    Nanosecond Max Current of Residual-Current Circuit Breaker

    <<Moderator note: Political statement removed.>> To protect against a nuclear EMP (NEMP) usually a big metal box is used, which is electrically connected to earth, to discharge the electrical pulse. Most houses in europe have a 3-grid electric system, L, Neutral (N) and Protective Earth (PE)...
  41. D

    Engineering Combination circuit with Series & Parallel light bulbs

    Homework Statement One 18 watt lamp and two 60-watt light bulb are plugged into a 120V circuit. For either DC or AC, the two bulbs are connected each other in parallel and in series with the lamp in the same circuit. Calculate; i. the current flow through each light ii. the total...
  42. M

    Calculating Charge and Time in a Discharging RC Circuit

    Homework Statement RC circuit, with a resistor, capacitor and a switch with ΔVC =80V R=1.5MΩ C=22μF The switch is initially open. The switch is closed at t=0 (a) What is the charge in the capacitor when the current is 33μA (b) How times does it take for the current to reach 33μA...
  43. Y

    Entropy change in an RC circuit

    Hello,I would like some help for a problem Homework Statement Initially:At t=0 [/B]the cylindrical capacitor of capacitance c=\frac{\epsilon s}{d} (d the distance between the 2 electrodes and s their surface; \epsilon = \epsilon(T) is the dielectric permittivity) is discharged and we close the...
  44. D

    Can a reed switch use a wheatstone bridge/potential divider?

    Homework Statement Describe the principle of operation of reed switch and LDR using wheatstone bridge and potential divider arrangement I can't find any website that says a reed switch uses a wheatstone bridge or potential divider arrangement. The only find I have found it that that a magnet...
  45. D

    What is the operation principle of the LDR?

    Homework Statement Construct suitable circuit and record your finding to illustarte the operational principle of the sensors: sound, light Results: Distance from light source (cm) - light intensity (lx) 0 - 1000 10 - 400 20 - 260 30 - 200 40 - 190 50- 180 experiment involved moving a...
  46. D

    How does a thermocouple exploit the Seebeck effect?

    Homework Statement descibe the operational principle of a thermocouple Homework EquationsThe Attempt at a Solution A thermocouple works using the seebeck affect. Two dissimilar metals joined together at one end forming a "hot" junction this is where the temperature is measured. At the other end...
  47. D

    I Can Diagrams be Used as Circuits in Explaining Sensor Operations?

    I have to construct suitable circuits to show the operational principles of some sensors: pH meter, sound, light and temperature. Would these count as circuits? or diagrams? (I'd say diagrams). https://www.electronics-tutorials.ws/io/io45.gif I am finding it hard to find circuits showing how...
  48. Freddythunder

    Powering a 3W LED circuit or driver?

    I've been doing a lot of searching on the interwebs for the best way to power these 3W epistar high power LEDs. And then I started looking for an alternate I can afford. I hope someone can help me as I'm not too good with electronics. I got a handful of these LEDs...
  49. J

    LR circuit - Which bulb gets dim quickly?

    Homework Statement Homework EquationsThe Attempt at a Solution When the switch is off , the current in the inductor doesn't drop to zero instantaneously . The current in the loop consisting of inductor , resistor and two bulbs will decay gradually . Now since there is a complete circuit...
  50. marsupial

    Engineering The effect of a switch in a Laplace circuit analysis

    Homework Statement The switch in the circuit in has been closed for a long time. At the switch is opened. a) Find i0 for t>=0 (b) find v0 for t>=0 I don't understand the effect of the switch in the position it is in. It's acting as a short circuit, I think, so presumably the capacitor doesn't...
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