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. K

    Calculate the current in all parts of this electric circuit

    In the circuit below, the output is 23 W across the resistor with the resistance 6 Ohm. Calculate the amount of current in all parts of the circuit as well as the polarity and EMF ε of the unknown battery. Circuit: My attempt: I get 6 unknowns with 5 equations. I don't know how to find the...
  2. Flying_Dutchman

    Transfer characteristic of this circuit

  3. C

    Engineering Calculating the size of a capacitor in a sample and hold circuit

    First, I calculate the jitter power with an equation given in the book Next, I calculate the signal power Now, I know that SNR = Psignal/(Pjitter + PthermalNoise), However, I seem to be getting a negative value for the thermal noise power?? My plan was to use this thermal noise power and...
  4. M

    Giving a jump start to a car - how does the circuit become complete?

    Car A has a dead battery and car B gives a jump to it. I connect the positive of battery B to the positive of battery A and the negative of battery B to the body of car A. 1. Am I essentially creating a separate circuit by choosing a different ground than that of battery A? How is the current...
  5. Jason-Li

    Comp Sci Laplace Transform of the input portion of this circuit

    So I have completed (a) as this (original on the left): I have then went onto (b) and I have equated T(s)=Z(s) as follows: and due to hence Does this look correct to you smarter people? Thanks in advance! All replies are welcome :)
  6. fluidistic

    Compute the useable power in a simple circuit with resistive vs. reactive loads

    This is not a homework question, but I am interested to calculate the power that can be extracted to perform useful work in two similar circuits. I have been told that it should be the same but this is not what I get. Consider a voltage source as a fixed voltage source in series with an...
  7. F

    Boundary conditions for a purely inductive load in an AC circuit

    Hi all, Kirchhoff's equation for this simple circuit is equivalent to \dot I=\frac{V}{L} Where V=V_0 \sin(\omega t). Integrating both sides should give I(t) = -\frac{V_0}{L\omega} \cos(\omega t)+c where c is an arbitrary constant (current). Here, most of the derivations I've found simply drop...
  8. I

    Motor circuit breaker - connections

    Why we use such connection between 4 and 5 terminals? Why the transformer isn't connected via 2 and 4 terminals from CB, the voltage will still be 380V because it's between two phases? In such situation the terminals 5 and 6 will stay unused, why not on this way?
  9. E

    Semantic question on cell circuit symbol

    Suppose the emf of cell ##X## exceeds that of ##Y##, such that conventional current is driven in in an anti-clockwise direction. There is a little ambiguity in my mind about the circuit symbol for ##Y##. In the above setup, the larger bar of ##Y## is at higher potential and the smaller bar at...
  10. B

    Value of the shunt resistor in this circuit

    Here are a couple of questions that I have been trying to answer and had a go at it. Not sure if I answered some incorrectly so was hoping to get some guidance For this one I have tried to make use of Kirchhoff's 2nd law to help me, but this is what I have ended up with when using it...
  11. B

    Balance length for a potentiometer circuit

    Here is the question itself Here is my attempt at it Does 4cm look right? Any help would be great, thanks!
  12. T

    Quantum 3-Qubit Error Correction Circuit

    Hello! I have this problem regarding the analysis of an error correction circuit. This problem set has been set for hand-in before the lectures regarding error-correction take place, so I am struggling. With that in mind I have read about the initialisation of the first qubit with two others...
  13. B

    Working out the shunt resistance for a galvanometer circuit

    Here is the problem I have tried to draw the set up for both cases which the question had described above, and came to these 2 equations. But I can't see how it would help me to work out the resistance of the shunt? Any help would be really great! Thanks
  14. K

    Discharging this capacitor in an RC bridge circuit

    The voltage source in the circuit below has been switched on for a long time when the switch S switches off. How long will it take before the current coming out of the capacitor has become less than 1 mA? My attempt: I am far from sure that my solution is correct. This is because i...
  15. A

    Problem in identifying a short circuit in a diagram

    Hi all! while simplifying this diagram, I thought that R2 and R4 are in parallel while so I simplified the diagram to this BUT THE SOLUTION CONSIDER THAT R4 AND R2 HAVE BEEN COUR CIRCUITED! Any help would be highly appreciated particularly a rule of thumb that helps me to identify a short...
  16. B

    Working out the current and voltage in a circuit

    Here are a few problems I have been trying which are shown below Here is what I have done The correct answers for these Q's are: I'm not sure what I have done wrong for Q4, I assumed that all 12 cells were connected in series thus each individual emf sums up to 24V Similarly the...
  17. N

    Finding the currents in this circuit (2 voltage sources and 3 resistors)

    In my attempt, I tried 1) I1 = I2 + I3 Then set up these two equations based on Kirchhoff's second rule: 2) U1 = R1 (I2) + R3 (I3) and 3) U1 + U2 = R1 (I1) + R2 (I3). From what we have 10 = 0.1* I_2 + 0.2 * I_3 22 = 0.1* I_2 + 0.02*I_3 I_3 = 50 - 0.5 I_2 That means I_2 = 233.3 A I_3 = -66.7A...
  18. H

    DIY dyno calculation with an Arduino sensor circuit

    I would like to know if this formulae i have are good enough to make calculations. My plan is to count time of each roll with Arduino.I don't have roller yet so i don't know moment of inertia.angular acceleration = radians/secounds TORQUE = moment of inertia (kg∙m2) * angular acceleration RPM =...
  19. Reneee

    What's the total amount of resistance in this kind of circuit?

    I am not sure how to treat the extra connections K12 and K34. My first guess would be (R1 and R2) are parallel and so are (R3 and R4) and (R5 and R6) ,so R_{total}= {R1*R2} /{R1+R2} +... Or maybe the behaviour is like this: (R1, R3, R5) are in series , and (R2 R4 R6) are, thus R_{total}=...
  20. Boltzman Oscillation

    Understanding Basic Electronics: A 9V Battery & Two 9V Bulbs

    Homework Statement:: How can I determine whether my basic circuit will work? A battery and two light sources. Homework Equations:: conceptual question, use basic ohms law, current law, voltage law, etc. This is not a homework question, i am just trying to understand electronics better. I am...
  21. nmsurobert

    Kirchhoff's Rules for analyzing this circuit with batteries and resistors

    Summary:: Choosing the direction of the loop and the current I am attempting to work out Example 1 in the link provided. https://courses.lumenlearning.com/physics/chapter/21-3-kirchhoffs-rules/ When solving for loop aefgh, I get: I1R1-I3R3-I3r2-E2 =0 I chose the current to continue to move...
  22. eyespy

    A circuit with switches, capacitators and resistors

    To solve this question first I calculated the potential energy the capacitor A stored. It's equal a: Ca.V²/2. Ok, so when switch S1 is open and S2 is closed I calculated the equivalent capacitance as if they were in series --> 1/Ceq = 1/Ca + 1/Cb --> Ceq = (Ca.Cb)/(Ca+Cb). So I used the formula...
  23. F

    Relay and Capacitor circuit - blinking LED

    Hello Forum, I am having issue understanding what is going on with the circuit below which is supposed to blink an LED by alternatively pulling the switch up and down which results in opening and closing the circuit the LED is part of (lower circuit portion). This is what I am confused about...
  24. J

    Circuit diagram questions -- 3 Light Bulbs in a 120V circuit

    I have A2 as 150, A4 as 150, A5 as 300 and A3 as 0. I just need these answers checked to make sure I’m right.
  25. M

    Engineering Thevenin Theorem seems to not work in this 1 bit RAM RC circuit

    I have a problem which consist in 1 bit RAM made of 3 MOSFETs. One of the questions is to calculate the maximum voltage that the memory element can receive. I have obtained the result by inspection (it is 4 Volts) but I'm unable to reach the same by applying the Thevenin Theorem. My...
  26. Andrea Vironda

    Why in an RL circuit does the voltage anticipate the current?

    In my idea the tension change after connecting the circuit to a battery is immediate, while the current takes some time before moving. That should be sufficient to prove my question but, so why in a RC circuit the opposite happens?
  27. J

    Engineering A circuit with non-linear devices

    I honestly don't know how to quite even begin this problem. Looking at Fig 3-2, the slopes of the graphs are 1/R, and hence where the slopes are 0, we have infinite resistance, in which case current wouldn't flow through that resistor and hence simplify the circuit. So I was trying to find...
  28. J

    Engineering Finding voltages in a linear circuit

    From the circuit I have: ##-v_b + v_a + V = 0## ##v_b - V = v_a## ##i_1 = (v_b - V)/R_1## ##I + i_2 = i_1## ##(v_b - V)/R_1 = I + v_b/R_2## From this last equation I get ##v_b = 10.8## and hence ##v_a = 5.8##. However, apparently that is wrong. (And hence my answers to #2 were all wrong as...
  29. J

    Finding the missing current and voltage in a circuit with superposition

    I don't get this. Since we have analyzed the circuit separately for each source, adding them should give me the final values of I1, V2, I2, V1 etc. However, that's not quite true—from cases 1 and 2, I should have I1 = 4 + 5 = 9 mA, but it's 8mA. Hence, I thought that the black box consumes 1mA...
  30. J

    Engineering Solving Circuit Equations: A Struggle

    I am having a hard time solving this. Letting \$i\$ be the current flowing into ##R_3##, ##i_1## the current flowing through ##R_1## and ##i_2## the current through ##R_1##—and the node between R3 and R1 be e_1; Using KVL and KCL, I've managed to find that ##i + I = i_1 + i_2## Hence...
  31. J

    Thevenin isolates nonlinear element

    I have no problem getting the ##R_{TH}## since from the special element's POV, the resistors are in parallel, and that's the answer. However, I don't really understand how to get ##V_{TH}##. Ignoring the special element, it seems that I have the resistors in series this time. But I'm not too...
  32. J

    A Circuit with Nonlinear Element—finding element's current & voltage

    I don't really understand or see the correct way to approach this. Letting the current in question be ##i_x## (as shown in Fig. 1), and the unknown (changing) resistance be $R_x$, I can write: ##-V_s + R_s i_s + i_x R_x = 0##, and ##R_p i_p = i_x R_x##. Hence we can also write ##-V_s + R_s i_s...
  33. J

    Circuit Analysis of a diagram with series and parallel circuits

    I found the Req which is 13.6 and also found the It which is 0.74. I'm having trouble finding the separate current and potential difference numbers.
  34. B

    What is the efficiency of the circuit?

    The answer in the textbook's
  35. E

    Is My Super Capacitor Power Bank Circuit Safe?

    I'll make a power bank with capacitors and I made circuit of it. But I'm worrying about whether the circuit is safe, because it's dangerous to use capacitor. So, can you check the circuit i made?? My capacitor is 2.7V, 600F and the power bank circuit has "Charging current : 1A maximum, output...
  36. E

    I'd like to find a power bank circuit with 2.7V input

    Hey, can you find me a power bank circuit which has 2.7V input?? Because I'm in a project which makes power bank with super capacitor, and you knows that we can't input voltage above the maximum voltage of capacitor, right? You can refer this video. Thanks.
  37. A

    Engineering Can this circuit be solved without nodal analysis?

    help will be appreciated
  38. Boltzman Oscillation

    Engineering How should an H bridge circuit be analyzed?

    If I am given an H bridge circuit such as that below: How would I go on analyzing it? I would personally replace all of the transistors by their circuit models but then what would I do with the motor? Do I replace the motor with it's load resistance or is there more to it? I guess motors are...
  39. A

    Engineering Troubles with a circuit analysis situation (RLC circuit)

    thanks
  40. Y

    What are the key steps to solving this beginner circuit problem?

    I calculated the voltage of the resistors
  41. E

    Bias-Tee Design for an RF Circuit

    Am having a difficult time with Bias-Tees. I do not know how to get the characteristic impedance (although I assume it uses the equation below) How would you use this if you are not given the R and the G? You could guess L and C. I know how Bias-Tees work and that a typical schematic would...
  42. A

    How to Solve an Electric Circuit Like This?

    Can someone please tell me to find R of this electric circuit? Please tell me the step-by-step. I have many problems of electric circuit like this. If you show me one, perhaps I can solve the rest of them.
  43. M

    What is the electrical equivalent circuit for this interaction?

    A textbook gives an example of an ideal mass striking an ideal string here: This is drawn as an equivalent electrical circuit as follows, where each R represents one of the two string segments the mass interacts with (ie. the string segment to the left of the mass and the string segment to...
  44. J

    Introductory Circuit Analysis—power ratings

    I am going through "Circuit Analysis for Dummies". On pg 18, it says, "If you calculate the power dissipated as 0.1 watts, then a 0.25-watt resistor can handle this amount of power. A 0.125-watt resistor should be able to handle that amount as well, but when it comes to power ratings, err on the...
  45. D

    Voltage and current as functions of time for a series RL circuit

    I already found ##I(t)## using Kirchhoff's laws, I got the equation ##V-RI-L\frac{dI}{dt}=0\Rightarrow L\frac{dI}{dt}=V-RI## then I solved the differential equation getting ##I(t)=\frac{V}{R}\left[1-e^{-\frac{R}{L}t}\right]##. My problem is founding the voltage as a function of time ##V(t)##, I...
  46. A

    Frequency in an AC circuit given capacitance, voltage, and current

    By combining the formula for the reactance of a capacitor with Ohm's Law for a capacitor, I can solve for angular frequency, and divide by 2π to find frequency. The resulting equation is: f = I/(2π VC) Using the given values, I end up with 5.2 kHz, instead of the correct answer of 5.2 MHz. I...
  47. M

    Minimize the circuit for this expression

    Summary: circuit diagram from minimize expression I am drawing a circuit diagram from a minimize expression. I have come up with two circuit diagrams that give same result. I am not sure which of the circuit diagram (1) or (2) is correct. Are both my diagram correct? Need help
  48. M

    Engineering AC circuit: Find the current through the inductor & capacitor

    Hi! I wonder if it is correct. Can someone confirm (maybe with a software) ? I(L) = I2 I(C) = I2 - I3 -- Thanks.
  49. A

    Help with LTSPICE on a high frequency circuit

    Hi, can you please tell me how would I be able to determine the effectiveness of a specific circuit, see in the attached spice file I tried to simulate a circuit , my secondary side is a self generating coil which in spice I had to simulate with mutual inductors aka a transformer, my basic idea...
  50. A

    Engineering BJT circuit with cascaded stages

    This cascade is divided into 3 sections thus: the leftmost section is an emitter follower : Ib1 = (15V-0.7V)/ ( R1 + 151R2) IE1= 151*Ib1 re1= 26mV /(IE1) Zb1= 150( re1+ R2) AV1= (-150*R1)/ (R1+Zb1) the center section is an unbiassed BJT : Ib2 = (15V-0.7V)/ ( R3 + 151(R4+Re2a) ) IE2=...
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