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. M

    Solve RLC Circuit Problem Homework

    Homework Statement http://imgur.com/a/3xSYb Homework Equations RLC equations: q= Qmax e ^ -Rt/2L cos wd t wd = [ 1/LC - (R/2L)^2] ^ 1/2 The Attempt at a Solution So, I am trying using Kirchoff law, but not sure what the question asks. I thought it may be a trick and after a long...
  2. A

    How Does a Capacitor Charge to Negative Voltage in an RC Circuit?

    Homework Statement At initially, the switch is open meaning there is no current flowing. So how does the capacitor is initially charge to -5V? and what does a negative voltage capacitor means? I thought it is only when the switch is closed (t=0) that when the capacitor is being charged...
  3. Likith D

    Does Adjusting Potentiometer Resistance Affect Volume in Amplification Circuits?

    The above is a circuit i found on the net regarding amplification of volume. I needed to know if increasing the potentiometer resistance (between "cold" and "wiper"; terminal 1 and 2?) in the circuit would increase "volume" Also, i could use a potentiometer resistance ( between "cold" and...
  4. G

    Understanding Circuit Breaker Terminals: IN & OUT Explained

    Why does a circuit breaker not show which terminal is IN and OUT?
  5. gimak

    Finding the average energy in an RLC circuit

    Homework Statement Homework Equations Q(t) = Aei(wt+Φ); dQ/dt = i*w*Q(t); E = (L/2)(dQ/dt)2 + Q2/2C i = √-1 E above is average energy The Attempt at a Solution When I plug in Q(t) & dQ/dt into equation above (E) I get: A2L/2(w02-w2)cos[2(wt+Φ)] w02 = 1/LC After I plugged both of them in...
  6. M

    Powering an LED strip with a 12v battery

    Hi, I want to run a cheap 5 meter led strip along the inside of my boat for cool night lighting. It will be powered by a 12v deep cycle battery. I was hoping y'all could double check what I was thinking before I set something on fire... Here is the led strip...
  7. Asmaa Mohammad

    The rheostat and the brightness of the bulbs

    Homework Statement In the circuit shown in the figure, what will happen to the brightness of bulb A and bulb B when the wiper moves from point X to point Y? Homework EquationsThe Attempt at a Solution [/B] When the wiper moves towards Y we get smaller resistance, hence the current intensity...
  8. Asmaa Mohammad

    The reading of the ammeter and the reading of the voltmeter.

    Homework Statement In this circuit What will be the reading of the ammeter and that of the voltmeter when: 1. Key S1 and key S2 are open. 2. Key S1 and key S2 are closed. 3. Key S1 is closed and key S2 is open. (Neglect the internal resistance of the source) Homework EquationsThe Attempt at a...
  9. Asmaa Mohammad

    Using Kirchhof's laws to solve a circuit

    Homework Statement In the circuit shown in the figure (attached with the solution). Determine: 1. the reading of the ammeter when the key (K) is open. 2. The reading of the ammeter when the key (K) is closed. Homework EquationsThe Attempt at a Solution [/B] What confuses me in the circuit...
  10. D

    What Happens to Current in a Parallel Circuit When More Resistors Are Added?

    Hello. Something has been bothering me for a while now: Consider a circuit with one battery and only one light bulb, for example. We have a value for the resistance of the bulb (R) and there is also one value for voltage (U) and one for current (I). Now, let's imagine that we connect a new...
  11. M

    Electronic Circuit with 2 diodes

    Homework Statement I have to find Vo in every diode state possible. We know diode Vf = 0.7 Homework Equations Va-Vc < 0.7 = diode OFF Va-VC > 0.7 = diode ON The Attempt at a Solution State 1: if D1 OFF and D2 OFF Vo will be equal to Vi State 2: if D1 OFF and D2 ON Vo will be equal to...
  12. T

    AC Mains meter circuit design for energy sources....

    What circuit design is used to ensure that the renewable energy source does not begin to absorb energy from the grid (for instance, when its terminal voltage drops below the distribution line voltage)?
  13. unseeingdog

    Final charge on capacitor for an RC circuit

    Homework Statement Homework Equations ##q = CE(1 - e^{-t/RC})##The Attempt at a Solution I assumed that, since the problem specifies that sufficient time has passed, it meant to say that enough time passed. thus making the exponential term in the equation go down to 0, and the charge in the...
  14. C

    Power of resistors in parallel vs series circuit

    Homework Statement Two Ohm's resistors in parallel consume power of 76 W and 24 W. What power will each of them consume if transfer them to the serial circuit with the same voltage of source. Sorry for my bad english translations I m not use to writing questions in English.. So what confuses...
  15. R

    12V diode combiner circuit question

    Hello, I'm currently doing an electrical refit on a 29' Bristol. I have an anchor/steaming light for the top of the mast. I'm connecting them to two separate single pole single throw breakers. My problem is that I need the steaming light (fwd light) to be able to come on indipendantly from the...
  16. Arman777

    RLC Circuit DC Homework Solution

    Homework Statement Homework Equations The Attempt at a Solution I used the loop rule where ##ΣΔV=0## and junction rule. From here I get 4 equations ##i_3=i_1+i_2## ##ε-i_3R_3-i_1R_1-L(di\dt)=0## ##ε-i_3R_3-i_2R_2-Q\C=0##...
  17. H

    Solving the Parallel Circuit: R=25, X[c]=100, X[L]=25

    Homework Statement what is the value combined impedance of the parallel circuit ?when R=25 ,X[c]=100 and X[L]=25 Homework Equations I think we use this equation to solve parallel impedance .... The Attempt at a Solution...
  18. K

    Calculating total resistance of a combination circuit

    Homework Statement Find the total resistance of the circuit Homework Equations Parallel resistance: 1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ..., Series resistance: R1 + R2 + R3... The Attempt at a Solution The 1470 ohm resistor is parallel to the 50 ohm resistor and the 1000 ohm resistor, but there is...
  19. K

    Current division in a series-parallel circuit

    Homework Statement Determine the current through each circuit element Homework Equations V = IR (Ohm's Law), The Attempt at a Solution I1 is .06A after plugging 6V and 100 ohms into V = IR, but I can't figure out the rest, because I don't know how the current splits. The left path obviously...
  20. J

    Engineering Designing 3-Stage Async Counter & Logic Circuit in PSpice

    Homework Statement The block diagram of FIGURE 3 shows a three-stage asynchrononous counter that is used to count a series of randomly occurring input pulses. The ‘Q’ outputs of the counter are used to drive a logic circuit that gives the output shown in TABLE 1. (a) Design the counter using...
  21. A

    Circuit Problem -- Combining 4 resistors to make 95 Ohms

    Homework Statement 1. Use resistors of 30 ohms, 40 ohms, 50 ohms, and 50 ohms to create a circuit with a total resistance of 95 ohms. 2. Find the amount of current going through two of these resistors if the circuit is attached to a source of 12 v. 3. What would be the voltage drops for the...
  22. Polygon

    I Electrical circuit differential equation

    q''+ 20 q = 100 sin(ωt) I have been asked to find all mathematically possible values of ω for which resonance will occur. From the homogeneous solution, q(t) = Acos(√20 t) +Bsin(√20 t), I can see that resonance occurs when ω=√20. My question is, should I also consider -√20? And if so, what is...
  23. doktorwho

    Help understanding phasor solution

    Homework Statement From the given circuit and provided information draw a phasor and calculate the inductance. Homework Equations 3. The Attempt at a Solution [/B] The paper was given to me at class as a solution to our homework and i can't understand how they drew the phasor and drew the...
  24. D

    Engineering Laplace tranforms, transient current series CR circuit

    Homework Statement A step voltage of 120v is applied to a series CR circuit. R = 20KΩ, C = 4µF 1. Deduce, using Kirchoff's voltage law and Laplace Transforms, an expression for the transient circuit current. 2. Using the equation obtained in 1. deduce the equations for the transient voltages...
  25. T

    Gain of Electric Circuit: Vo/Vs and Resistance R

    Homework Statement So this problem is on Introduction to Electric Circuits 9th Edition (Richard C.Dorf) This asks me to express the gain of this circuit Vo/Vs by terms of the resistance of R. Homework Equations KCL, KVL, some ideal OP AMP characteristics... The Attempt at a Solution...
  26. Alexander1

    Voltage Regulator Circuit Calculations

    Hey Guys, so I'm just in need of some help in relation to finding the output current after the voltage has been dropped to 6V. The circuit has an input voltage of 24V and I've attached a photo of my circuit diagram. Hopefully I haven't made any errors in that, but I've tested the circuit and it...
  27. F

    Engineering Solve Series RC Circuit for Capacitance & Currents

    Homework Statement Three lamps are rated 110 V, 60 W. They are connected in parallel and a capacitor is connected in series with the group. The circuit is then connected to a 230 V 50 Hz power supply. Detremine: a) The capacitance which is required to provide the correct voltage across the...
  28. B

    Opamp Circuit: Finding Voltage at Resistor and Power Supplied

    Homework Statement Homework Equations V_- = V_+ The Attempt at a Solution There is negative feed back so V- =V+ ... Vout is then equal to the voltage at the positive terminal So the solution does a voltage divider... finding the voltage at the 4.62 ohm resistor.. However I did KCL at...
  29. C

    Engineering Model of RL Circuit using the Energy function

    Homework Statement From the textbook: We define an energy function \begin{equation} V(\textbf{x},t) \leq 0 \end{equation} for the system \begin{equation} \dot{\textbf{x}} = \textbf{f}(\textbf{x},\textbf{u},t). \end{equation} The function V may be the total energy of the system, or it may be...
  30. Ravensight

    Engineering Finding unknown Phasor in a series-parallel circuit

    So this is a "bonus" question from a past final exam for my Electrical Circuits course. I've spent a good few hours trying to solve it but haven't really had much luck. Any method can be used I figured if I found the voltage of the known XL, it would be equivalent to the voltage of the unknown...
  31. Z

    Simple effective resistance of a circuit at low voltages

    I passed small voltages (0-5V) through a known resistance, measured the current each time, and got different "effective resistances" for each case. However, when graphed, the effective resistances appear to approach the known resistance of the circuit as a limit at higher voltages. What is the...
  32. e0ne199

    Engineering Question about free source RLC circuit

    Homework Statement below is my question : Homework Equations all of the equatios used to solve this problems are equations for free source RLC circuit. The Attempt at a Solution so far i have solved problem (a), whose answer is -1400V/s, the problem is when i want to solve (b) and (c) do...
  33. S

    Capacitor Circuit: Understand 40µF Capacitor

    Homework Statement 2. Homework Equations [/B] No equations needed The Attempt at a Solution I know that capacitors are used to store charge but what exactly is the 40 micro-farad capacitor doing? No emf/voltage is shown so is the 40 micro-farad capacitor acting like the emf/voltage? or is it...
  34. Manoj Sahu

    What does IC555 do in this circuit?

    This is the circuit diagram of a solar charge controller. This circuit is fed by a wind mill or a solar photovoltaic panel. Either wind mill or solar PV panel work at any instant controlled by switch SW1. I don't understand what is the working of IC555 here. The main objective of this circuit is...
  35. Tyler R

    Solving KVL in a Multiloop Circuit with Battery & LC Circuits

    1. The problem statement, all variables, and given/known data I built a multiloop circuit for a project. The 4.2v is from mini-USB. The 3.7V is a lipo battery. The circuits are A/V Transmitters (LC circuit) which have an impedance of 75 ohms. The resistor is a 470-ohm resistor. I don't think...
  36. C

    Writing Kirchhoff Rules for a Multi-Loop Circuit

    Homework Statement I need to write Kirchhoff rues for the following circuit. This is not for a physics class, but for a programming class. I can do that part, but I am not sure if the equations are correct. Homework Equations The Attempt at a Solution V1-I1*R1-(I1-I2)R3-I1*R2=0...
  37. Vanessa Avila

    (LC Circuit) Finding cap charge after connecting to inductor

    Homework Statement A capacitor with a capacitance of C = 5.95×10−5 F is charged by connecting it to a 12.0 −V battery. The capacitor is then disconnected from the battery and connected across an inductor with an inductance of L = 1.50 H . What is the charge on the capacitor after a time...
  38. Cocoleia

    Laplace transforms in circuit analysis, finding missing values

    Homework Statement The Attempt at a Solution At this point, usually I would replace the values and sometimes separate into partial fractions, and then take the inverse Laplace transformation. So I know that the inverse Laplace needs to give me 6+12e^-2t. I am given the answers in my...
  39. Kara386

    I Why Does No Current Flow Between C and D in This Circuit?

    In the circuit in the image attached, why does no current flow between C and D? I've been told it's a short circuit I just don't see why, there is a resistor in that branch. The source is connected between terminals A and B.
  40. Cocoleia

    Using Laplace to solve circuit analysis

    Homework Statement The Attempt at a Solution As you can see, the answer is given in the problem. I have the 0.8t par right but somewhere along the way I messed up. I'm not really to sure about how to solve these types of problems using Laplace. Is there a general procedure that I should be...
  41. Manoj Sahu

    Will this solar charge controller circuit work?

    The circuit is intended to control the charging of a 12v 7ah battery by a 10w, 24v volt solar panel.
  42. S

    Type of circuit -- What would you call this?

    Homework Statement Homework Equations No relevant equations The Attempt at a Solution Trying to figure out what type of circuit this is. As far as i can tell its just a circuit with voltage, inductors, and resistance and a switch Only thing is i don't know what type of circuit this would be...
  43. D

    Engineering Simple DC Circuit Analysis with Transistor

    Homework Statement Homework Equations The Attempt at a Solution All loops are clockwise; KVL Loop around 1V, 120kOhm and VBE (I1 is assigned to the loop): -1V + 120kOhm * I1 + VBE = 0 I1 = IB = 0.3V / 120kOhm = 2.5 * 10-6 A; Loop around 10kOhm, vCE (I2 is assigned to the loop); KVL...
  44. TheBigDig

    Engineering Finding Phase Difference in an RC circuit

    Homework Statement Homework Equations ##V = ZI## ##Z_R = R## ##Z_C = -\frac{j}{\omega C}## ##Z = \sqrt{R^2 + (\frac{1}{\omega C})^2}## ##P_{av} = \frac{1}{2}V_m I_m cos(\phi)## ##\phi = arctan(\frac{-1/\omega C}{R})## ##\Delta \phi = \phi _1 -\phi _2## The Attempt at a Solution I've found...
  45. T

    Dumb question regarding short circuit test equivalent resistance

    Hi, Silly little question about the transformer short circuit test. When I perform it with the secondary shorted and I get Req = Power / current2 is this Req = Rpri + Rsec? If I measured Rpri and Rsec with a multimeter? Thanks
  46. S

    Solving Inductor Circuit Homework Problems

    Homework Statement For the circuit shown in the figure, the inductors have no appreciable resistance and the switch has been open for a very long time. (Image of circuit) (a) The instant after closing the switch, what is the current through the 60.0-Ω resistor? (b) The instant after closing...
  47. Manoj Sahu

    Circuit Explanation: 12V CFL and LED Usage?

    I stumbled upon this inverter circuit while searching for the same on internet. Can anyone please explain working of this circuit to me.
  48. A

    Why do the capacitors in this circuit have the same voltage?

    Homework Statement Homework Equations C = Q/V The Attempt at a Solution I understand that capacitors in parallel have the same voltage, but wouldn't they be in series after the switch is flipped, since no current goes to the left most portion of the circuit.
  49. R

    Plotting a RLC Circuit: Analyzing a Differential Equation

    I'm not sure about the physical behavior of a RLC circuit and I have to give a presentation that involves one. So I've decided to plot the current. I found a book that gives a differential equation to describe the circuit. ##L\frac{d^2i}{dt^2} + R\frac{di}{dt} + \frac{1}{C}i = \frac{dv}{dt}##...
  50. stephen8686

    B VIR Chart for Circuit Analysis: A Quicker & Intuitive Alternative to Loop Rule

    Hello guys, I'm reviewing for the AP physics C exam and in one of my review books I came across this trick called a VIR chart for circuit analysis. It's a sort of weird alternative to the usual Loop Rule. If you haven't heard of it before here it is...
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