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. J

    Engineering Rate of change of current in an R-L Circuit

    Homework Statement Homework Equations Current cannot change suddenly through inductor unless input is impulse voltage source. The Attempt at a Solution since input is DC source we have i(0+) = i(0-) so we have di/dt at t = 0+ is 0. Is it correct? Book has mentioned answer as B which is weird...
  2. D

    Two battery circuit charging one capacitor

    See attached photo for circuit diagram. The switch S has been open for a long time. Determine the magnitude of the electric charge stored by the capacitor. Use the following data: C = 3.43 mF, ε1 = 11.0 V, ε2 = 31.9 V, R1 = 3.66 Ω, R2 = 5.04 Ω. I understand how to determine the magnitude of...
  3. R

    Current Flow Through a Common Part of a Circuit (batteries and light bulbs)

    Hello, I have a simple question regarding current flow through a common part of a circuit. I encountered this as I am reading "Code: The Hidden Langauge of Computer Hardware and Software" by Charles Petzold. The images I've attached display what I'm talking about. I'd like to know if there's a...
  4. K

    Operation of this hydraulic circuit?

    Can anyone explain the operation of this circuit? I'm finding it hard to understand hydraulic circuits, like where is the source of fluid coming from? I know what all the components are and what they do. It's just trying to understand how it actually operates.
  5. F

    Find the initial current in the circuit (at t=0)

    Homework Statement In the circuit shown,the initial charge on the capacitor is Q0 = 200μC . If the switch is closed at t=0 , the capacitor starts discharging through the resistance R=4MΩ . What is the initial current (in μA) (i.e. at t=0) in the circuit? Homework Equations I = I0 e-t/τ τ =...
  6. A

    Finding the Optimal Combination of Resistors for a Desired Total Resistance

    Homework Statement I'm asked to find a combination of resistors (parallel and/or series) that uses resistors of 25 Ω, 100 Ω, 50 Ω, and 50 Ω. They should add up to give a total resistance of 62.5 Ω. Homework Equations Req for parallel = 1/R1 + 1/R2 + ... Req for series = R1 + R2 + ... The...
  7. F

    Find the time constant of the circuit

    Homework Statement In the circuit shown S is closed at t = 0 . Find the time constant (in s) if C = 2μF. Homework Equations τ = Req C The Attempt at a Solution R = ##\frac{10*10}{10+10}## R = 5MΩ τ = 5*106 * 2*10-6 = 10 s Could somebody check my answer?
  8. D

    Finding R(t) in discharging RC circuit

    Homework Statement A charged capacitor with capacitance C is being discharged through a variable resistor that has its resistance dependent on time: R = R(t). Find function R(t) if the current through the resistor remains constant until the capacitor is completely discharged and the resistance...
  9. D

    Calculating current in five resistor/two battery circuit

    Homework Statement The circuit above has five resistors. Calculate the current through each. Homework Equations I1 = I2 + I3 (Node Law) ∑Vi = 0 (Loop Law) The Attempt at a Solution I tried to equate the currents using the node law, with I3 = I1+I2+I4+I5 But I see a flaw here, because the...
  10. NYAME EPHRAIM

    The JK flip flop nand gate circuit that I built does not simulate

  11. J

    Engineering I don't know what this electronic circuit does

    I have a homework question that asks me to draw up a truth table for the attached circuit. As you can see I did this (I think correctly). There is also an attached question asking what function the circuit serves - I am not sure what function this is Any pointers appreciated.
  12. P

    Voltage drop conceptual questions

    I'm having trouble understanding how voltage drops. My understanding of voltage is a difference in potential, with potential being how much work is necessary to move a test charge to a specific orientation. So, if we have a circuit with say, a 12V battery and a 1 ohm resistor, and I had a +1...
  13. D

    High voltage circuit with voltmeter in between

    Homework Statement You have a voltmeter with an internal resistance of 10 MΩ. You would like to measure a very large voltage source, but you notice that this overwhelms your voltmeter, and you begin to get inaccurate results if the voltage is too high. You design the circuit shown above as a...
  14. G

    A Kirchhoff problem: Find the currents and voltages in this circuit

    Homework Statement In the circuit of the figure, determine the intensities I1, I2, I3, I4, I5 and the voltage Ug. Homework Equations Superposition and Kirchoff The Attempt at a Solution 20-10I1+5I3-10I1=0 5I3+Ug+5I5=0 20I2+10I2-150=0 From the last equation, 30I2 = 150, I2 = 5 A KNOTS...
  15. J

    Equivalent capacitance in a circuit

    Homework Statement Homework EquationsThe Attempt at a Solution I think the circuit given above is incorrect due to the presence of the two resistors . I have never seen/done a problem where equivalent capacitance is to be calculated across two points in a circuit , having resistors along...
  16. J

    Using Kirchoff's Loop Rule to Determine Currents in a Circuit

    Homework Statement Homework Equations Kirchoff's Rule The sum of all V = 0 The Attempt at a Solution [/B] I think I'm having a problem determining the current at r_2 and R_3. I had originally thought the currents at both resistors would be I_3, writing E_2 — r_2 I_3 — R_3 I_3 — I_1 R_1 = 0...
  17. E

    Equivalent resistance of a circuit

    Homework Statement Consider the electric circuit shown in the figure. Assume that V = 13.7 V, R1 = R2 = R3 = R4 = R5 = 7.00 Ω. What is the equivalent resistance of the circuit? Homework Equations total voltage of a series circuit is the sum of the voltage of all the resistors total current of...
  18. jdawg

    Engineering Heat and Mass Transfer: Thermal Radiation Circuit

    Homework Statement 1.) A piece of bread (ε = 0.85) is being toasted in a toaster, as shown below. The heating element of the toaster consists of a wire 2 mm in diameter that is wound to approximate cylinders spaced 2 cm apart. This element acts as a blackbody. The housing for the toaster is...
  19. E

    How to know when an LC circuit hits resonance

    I have been having issues with a series LC circuit. I have a supply voltage of 6.96 volts, across the inductor is 7.04 volts and the capacitor voltage is 7.17 volts. The capacitor has a capacitance of 45uFarad and a supply frequency of 250 hertz. I don't know what the inductance is of the...
  20. Paul Colby

    Voltage Monitor for an LC circuit

    Hi, I have an air wound 0.736 mH coil in series with a 3.5pF capacitor being driven with a function generator. Ideally the series resonant frequency should be around 3.13 MHz. The internal impedance of the function generator is 50 ohms or so. At resonance the voltage across the cap should be...
  21. G

    Engineering Determine the input impedances of a circuit

    Homework Statement I'm studying a circuit with BJT's and I'm asked to determine the input resistances of the two amplification steps of the circuit. The circuit I'm analyzing is the following one: Homework Equations 3. The Attempt at a Solution [/B] To determine the input resistances I...
  22. C

    Engineering Simple transformer circuit with 3 resistors

    Homework Statement 2. Homework Equations [/B] V1N2=V2N1 I1N1=I2N2 The Attempt at a Solution For a part[/B] I try to draw 3 mesh but I cannot write down the equation. Can someone help me out?
  23. H

    Find the transient current in this circuit

    Homework Statement Homework EquationsThe Attempt at a Solution I often do circuit. But still there is always stuff i don't get.. I was asked to find 1) I1 I2 I3 immidiately after S closed 2) I1 I2 I3 after sufficient of time 3) I1 I2 I3 immidiately after S opened Just give me clue please...
  24. D

    Engineering Problem regarding a transistor state in a NAND circuit

    Homework Statement Calculate the output function and draw a graph of output voltage in the function of the input voltage of the following digital circuit: Homework Equations 3. The Attempt at a Solution [/B] By analysis of what happens when inputs A and B are on the logical "1" i have...
  25. EF17xx

    Emf in a circuit (multiple choice question)

    Homework Statement Correct answer is Homework Equations emf = I(R + r) The Attempt at a Solution When current flows the voltage across the battery is less than the emf so it's not A I really don't understand why the answer is C because B, C, D all seem correct to me. Please help me with...
  26. S

    Circuit Diagrams versus Logic Diagrams

    Why do we sometimes neglect resistors and power sources when we draw circuits and other times not? Is there different terminology for diagrams that are only concerned about the logic involved and diagrams where the voltage and resistance is accounted for?
  27. C

    RC Circuit with parallel resistor

    Homework Statement A circuit contains a capacitor of capacitance C, a power supply of emf E, two resistors of resistances R1 and R2 , and a switch S2 . Resistor R1 is in series with the power supply and R2 is in parallel with the capacitor and the power supply. S2 switches the branch that...
  28. D

    Materials for DTL, TTL circuit analysis

    Hi fellow forum-ers :), I have a test in about two weeks where i am going to be given a dtl or ttl circuit which i have to analyse and calculate its function. The professor said that the circuit given to us will always be a useful and existing one meaning he's going to give us some NAND, NOR or...
  29. Muhammad Danish

    Current Dividing in an Electrical Circuit

    A circuit contains a 7.5V d.c power supply and three resistors. The total resistance of the circuit is 30 ohms. Why will the largest current in the 18 ohm resistor? As far as I know is that the smallest current will be in 60 ohm resistor because it has the maximum resistance. Please explain...
  30. J

    Equivalent resistance between two points on a circuit

    Homework Statement Homework EquationsThe Attempt at a Solution [/B] The circuit is symmetric about AC and BD , but I am not sure how to use this to simplify the circuit . Could someone help me in solving this circuit using symmetry considerations .
  31. S

    Engineering 2^k - 1 as Output of a Circuit with 3 k-bit Inputs

    If I have a circuit with 3 inputs with k bits, A, B and C, how can I get the output to be 2^k - 1 using relatively standard components? And, or, not, mux, decoder, adder, etc... This is for part of an exercise that I’m doing. I couldn’t find anything in the notes to help. Could anybody give...
  32. F

    Current in Series Circuit: .5A Charge Flow?

    If we measure the voltage in a simple series circuit to be 5v and the resistance to be 10 ohms. The current given is .5A. Is this the amount of chage traveling from the first point to the second point per unit time, or is it the amount of charge flowing through a cross section of the conductor...
  33. adamaero

    Engineering KVL and sensitivity of a simple circuit

    Homework Statement Homework Equations The Attempt at a Solution Note to self - simple diode concept: http://www.cs.tut.fi/kurssit/TLT-8016/Chapter3.pdf#page=5 Unsure about this KVL (above). For the last sensitivity part, equations be falling out of the sky...
  34. paulmdrdo

    Engineering Op-Amp Circuit Analysis: Troubleshooting Incorrect Node Usage

    In the problem below, when I use nodes V1 and V2 I get the correct answer of Vo = -2.5v But when I use nodes V1 and Vo I get an incorrect answer. Please explain to me why my latter method did not work. Thanks.
  35. T

    Hollow cylinder magnet making contact with the circuit

    Homework Statement 1. Circuit moves downward while cylinder magnet is fixed. 2. Cylinder magnet moves upward while circuit is fixed. Gain emf in circuit. Homework Equations All those maxwell equations... F=v x B The Attempt at a Solution [/B] So first question is not that hard...
  36. Valour549

    AC Circuit Analysis- Find Impedance

    Homework Statement 2. The attempt at a solution Am I doing something wrong? I know it's just voltage division with AC phasors and we have to equate the real parts and imaginary parts to find the unknown, but I feel like the question shouldn't be this hard.
  37. ForumGuy

    Can the Sum of Second Derivatives of Charges be Claimed in a CLC Circuit?

    1. The problem statement, all variables and given/known data Homework Equations Capacitor (C): v(t) = (1/c)*q(t) Inductor (L): v(t) = L(d^2q(t)/dt^2) The Attempt at a Solution Using Kirchoff's Loop law, the sum of voltages around each loop must be 0. I think I can thus claim the following...
  38. F

    Voltage Variation in a Series Circuit

    If I had a simple series circuit with only a single resistor, and I used a voltmeter to find the voltage between a point at the end of the circuit and another point, which was moved from the beginning to the end of the circuit, what would I find at these various point? Would the voltage remain...
  39. J

    Output voltage in circuit with diodes

    Homework Statement Homework EquationsThe Attempt at a Solution Since both D1 and D2 are forward biased for the positive half cycle for the voltage input , current will flow through them . Both the diodes offer very little resistance , but do they act like connecting wires when forward biased...
  40. X

    Engineering Attempt at Thevenin Equivalent Circuit

    Hi, I am having trouble trying to determine Voc on this circuit. I have done the following to attempt it: 1) Converted my Voltage source to rectangular format (from polar) 2) Converted my capacitor and inductor to Xc and XL 3) I tried using KCL to find Va that's at the three-way on the circuit...
  41. A

    Independence of Currents in Inductor-Switch Circuit

    In circuit like this If I closed the switch "s" Are the currents in mesh "I1" and "I2" independent of each other? if yes Why /why not? Thanks.
  42. A

    Simulation of transistor switch circuit

    Hello, I'm new to electronics and I'm reading a book currently to learn more about the topic. I'm currently on a section where I'm building circuits where I'm using a transistor as a switch. I decided to experiment with the circuit they gave me and put it in a simulation software called Proteus...
  43. J

    Engineering Circuit interconnection: power delivered

    The circles are referring to independent voltage or current sources, which maintain the same current/voltage regardless of the rest of the circuit. I'm confused because power delivered means they want the value of the "negative" power, which would mean only i*v1 would be the only power...
  44. Tomi Kolawole

    Find the charge of Capacitor 2 in the circuit

    Homework Statement Homework Equations I am to use korchkoffs method to solve this problemThe Attempt at a Solution I already solved for the overall current which is the same throughout because C1 and C2 impeded current flow in sections of the circuit and i have found the charge on c1 BUT I...
  45. amirul

    Understanding Circuit Operation

    can anyone explain how this circuit work.thanks
  46. G

    Weird circuit board with only resistors

    Found this. What could it be? So many resistors and nothing else?
  47. D

    Is voltage the same in parallel circuits with different resistance values?

    Homework Statement I have to write about voltage within a parallel circuit and the formula for voltage in parallel is Vt=V1=V2=V3. But I was wondering if that's only the case if the resistors have the same resistance becasue I used resistors with different values Homework Equations V1=V2=V3...
  48. Const@ntine

    Engineering Building a Circuit in SPICE -- Why am I getting this error?

    Homework Statement I've got the following Circuit: And I have to make it in Spice. 2. The attempt at a solution So far I've got: Circuit Of Ex1 *Circuit Topology V1 1 0 dc 10 R1 1 2 4.7k R2 2 0 4.7k V2 2 0 ac 5 *Types Of Analysis .dc lin 500 100 10k *Output Statements .probe *Termination...
  49. D

    Kirchhoff's First Law to solve a circuit with 2 loops

    Homework Statement I've recently watched a video which explains Kirchhoff's first law however, I'm not sure about his calculations. I got the same answer just wanting to make sure I am doing it right. the guy wrote L1: -75I2 +3V=0 ⇒ I2= -3/-75=0.04A He calculated L2 like -12V -125I3 +75I2=0 ⇒...
  50. F

    Engineering Find the Thevenin Equivalent circuit

    Find Thevenins Equivalent circuit external to RL, then find I. Here's my work : 5Ω & 5Ω series → R(1) = 5+5 = 10 Ω 10Ω & R(1) parallel→ R(2) = (10*10)/(10+10) = 5 Ω 2Ω & R(2) series → R(3) = R Th = 5+2 = 7Ω V = I R R = (R Th * RL)/(R Th + RL) R = 70/17 Ω V = 5 * (70/17) = 350 / 17 V = 20.6...
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