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. Kaushik

    Understanding the Phase Difference Between Voltage & Current in a Circuit

    Consider a circuit with a witch, capacitor and an AC voltage source. The sinusoidal AC voltage source is depicted in the following graph: We know that, ##Q = CV## ##\frac{dQ}{dt} = C \frac{dV}{dt}## ##i = C\frac{dV}{dt} \tag{1}## So from the graph, the voltage increases rapidly around ## t =...
  2. Samama Fahim

    Calculating the Thevenin's Resistance of a Breadboarded Circuit

    How would we calculate the Thevenin's resistance for the above circuit? The right answer for this circuit is 1.5 kOhm. $$R_{567} = R_7 + (R_5 \parallel R_6) = .5 + .67 = 1.2 k\Omega$$ $$R_{34567} = R_3 + (R_4 \parallel R_{567}) = 1 + .75 = 1.75 k\Omega$$ $$R_{TH} = R_1 + (R_2 \parallel...
  3. A

    Calculation with this electric circuit (battery and resistors)

    Hey, I am struggling a bit, als I try to solve this problem - I‘d say all five statements are correct, but it is said, that one must be incorrect
  4. T

    Another angle of "Why do you need a line 2 on a circuit?"

    I know that on an alternating current circuit, you have to have both a line 1 and a line 2 to have a circuit. Here is a pictorial diagram of an alternating current circuit: In a previous thread, I asked why would an AC circuit like in Diagram 2 not work? Here is a photograph of diagram 2...
  5. Helena Wells

    Voltage Substractor simple circuit

    I have created a voltage adder using this circuit where Va and Vb are the input voltages. And Vout is between the emitter and the resistor. How can I modify it to a voltage substractor?
  6. Kaushik

    Question about charged capacitors and inserting a dielectric into one

    First when it is connected to the battery, the capacitors start accumulating charges such that the potential difference equals that of the battery. Then the current stops flowing. ##Q_1 = CV## ##Q_2 = nCV## Where 1 and 2 represent the capacitor with capacitance C and nC respectively Then, when...
  7. M

    Engineering Calculating Power Lost in a Resistor (within Transformer Circuit)

    Hi, I have a simple question that I don't have a fundamental understanding of: do resistors dissipate reactive power (in addition to active power)? For context, when we are looking at a transformer (single phase) equivalent circuit (similar to the one in the image attached), we are asked to...
  8. E

    Help designing an electrical circuit for camper van

    Hi everyone Hopefully I am not out of line posting in this forum. I am looking for some advice planning the electrical system for my camper van. I know very little about electrical circuits and all related to it, and after 4 days of research I am still nervous to spend a lot of money and...
  9. Kaushik

    Does potential drop when a charge flows through a wire w/ 0 resistance?

    Let us connect a battery of potential difference V to a wire. There is no resistance. Nothing! Now the battery creates some potential difference and the charges in the conducting wire move due to the Electric field created in the conductor by the battery. So, as the charge moves, its potential...
  10. T

    A different angle of Why do you need a line 2 on an AC circuit?

    Preface to thread: I am darn well aware of the fact that on an AC circuit, there has to be a line 2 after the load to bring current back to the power source. This thread is about WHY does there have to be a line 2 after the load to bring current back to the power source. I hope that I don't...
  11. D

    How to calculate R1 and R2 in this RC circuit

    Using the Capacitor voltage vs. time graph, I calculated the time constant τ when the switch is closed (capacitor charging) and open (capacitor discharging). I calculated τclosed = 2.5s and τopen = 3.75s. Since the resistors are in parallel when the switch is closed, I assumed that 1/Req = 1/R1...
  12. Boltzman Oscillation

    Where is the demodulator in this AM receiver?

    I am trying my hands on building receivers and transmitters. For now I would like to build this receiver here: now I see that the 500pH inductor in parallel witht he 200uH capacitor are in charge of filtering the unwanted frequencies. The top-left NPN is in my guess an emitter follower to...
  13. Frigus

    How to simplify this capacitor circuit?

    I tried to find logic behind how do we simplified the circuit as given for 2 hours and I unable to find any clue. I can do it just by following rules but I am unable to get intuition. I tried to make sense of it but how can we even make two points as one.
  14. J

    Dr. Middlebrook's "Technical Therapy For Analog Circuit Designers"

    Dr. R. David Middlebrook was a very well known professor of analog engineering at Caltech. He was also a cofounder of the power supply design and analysis group "Teslaco". Dr. Middlebrook developed a program "Technical Therapy for Analog Circuit Designers". The dvd was available for several...
  15. Boltzman Oscillation

    What approach should be used when solving a circuit?

    I am close to graduating as an EE major but I have never been able to organize a step by step method on analyzing a circuit. It seems to me that every time I am trying to analize a circuit I end up with a bunch of equations and nothing more. I know that I should: 1. Know what I am solving for...
  16. naftacher

    Confused as to where I begin to solve this circuit branch problem

    I am thinking that this circuit needs to be simplified somehow? Finding an equivalent resistance and moving from there?
  17. naftacher

    Struggling to find the equivalent capacitance of this circuit

    I asserted C3, C4, and C5 to be in series. **I found the capacitance of "C3-4-5" to be 1.67x10-6 F. This I did by using 1/C = 1/C3 + 1/C4 + 1/C5 Then I noticed that I had another series circuit of "C3-4-5" and C1, and C2. Again, I used a similar formula. I obtained an equivalent capacitance of...
  18. Boltzman Oscillation

    Engineering How does this Bipolar RF Amplifier + Output Transformer circuit work?

    I am trying to create a receiver for a personal project I am working on. This is the RF amplifier that I was given by a book I am following. How does this circuit work? Usually for a BJT amplifier I find the DC bias point and then use the small signal model after I bias the circuit? I understand...
  19. Adesh

    Capacitors connected in series: Why is the voltage the same?

    Here is a circuit diagram: . We have three capacitors, with capacitances ##C_1##, ##C_2## and ##C_3##. Plates are labelled as ##A_1, A_2, A_3 ... A_6##. Point P is connected to the positive terminal of the battery and point N is connected to the negative terminal of the...
  20. cnh1995

    Engineering AC transient in an RC circuit

    Here, at voltage source zero crossing, cos(2to + pi/4) =0. So, 2to+pi/4 = pi/2 This gives to=pi/8 = 0.3926s. But the given answer is twice the answer I got i.e. 0.7852s. Have I missed anything here?
  21. rachelmaddiee

    Voltage drops in a series circuit

    Known: V source = 30.0 V , R1 = 15.0 W, R2 = 15.0 W, R3 = 15.0 W To determine the current, first find the equivalent resistance. I = Vsource/R and R = RA + RB = Vsource/RA + RB 30.0 V/15.0 W + 15.0 W + 15.0 W = 1.5 A This is as far as I could do the work for this question. I’m having trouble..
  22. Boltzman Oscillation

    Engineering Variable Gain Amplifier Analysis help

    I need to find A_v, I want to relate Vin to Vout. To do this I did KVL on the major loop: $$V_{DD} = I_D*R_D + V_{SD1} - V_{SD2} - I_D*R_D$$ Since M1 = M2 then everything would cancel out and I would just get V_dd = 0 which is probably wrong. This is assuming V_sd1 = V_sd2, is that correct?
  23. Adesh

    How can electrons flow all the way through the circuit?

    Electric currents and the things within are generally explained through the help of intuitive water current examples, where potential difference is explained through the pressure difference and electric current is explained as the flow of water. But I like to think in terms of some driving force...
  24. jisbon

    Engineering Finding the transfer function for this circuit

    Transformed circuit: Using KVL, Now, I am unsure about the current to use KVL in this case. As far as equation goes: Vi(s) =(I1*R)+(I3*R)+Vc(s), where Vc(s) = V0(s)/u as shown in the circuit. How am I supposed to find the current I1 and I3 for the two resistors in this case? Thanks
  25. hmzi123

    Solve the circuit and find all the currents in the circuit

    Hello, i have this circuit as a homework. And i have to find all the I's, and Uef, i got stuck at writing Kirchhoff's laws in this circuit, do you think you can help me write them, and also can you explain how can i calculate Uef?
  26. hmzi123

    Engineering Solve RC Integrator Circuit Problem | Romania Student

    Hello, i am student from Romania ( first year) and my physics teacher told us to solve this problem. We know that C=150 nanofarad, R= 1000 ohms, and the frequency we should take is more then 1061 ( 10kHz, to be more exactly). My problem is that i don't know what to take as V1 ( i took it coswt...
  27. H

    Designing a DC Motor Torsional Spring Circuit with Arduino Uno

    I'm a relatively new entry into the world of electronics so my understanding of what is possible may not be an accurate one. In a nutshell, I would like to have a DC motor act as a torsional spring with some variable virtual spring constant (k). The motor, or "spring", would act against an...
  28. kyphysics

    Which Circuit Breaker Switch to Turn?

    My home water heater is messed up. If I want to reset the circuit breaker for it, which should I turn? There are three: 1.) garage (where the heater is located) 2.) water heater/dryer 3.) heat pump
  29. S

    Calculating Total Resistance in a Circuit: Delta - Y Formula or Simpler Method?

    To find total resistance between 22 Ω, 14 Ω and 4.5 Ω should I use delta - Y formula? Or there is other simpler way? Thanks
  30. evinda

    MHB Construct circuit that implements truth table

    Hello! (Wave) I want to construct a circuit that implements the following truth table:\begin{equation*} \begin{array}{c|c|c|c|c} P(Input) & Q(Input) & K(Output) & A(Output) \\ \hline 1 & 1 & 1 & 0 \\ 1 & 0 & 0 & 1 \\ 0 & 1 & 0 & 1 \\ 0 & 0 & 0 & 0 \end{array} \end{equation*}In...
  31. R

    I Hamilton path and circuit rounded path problem

    Here is a graph. I wonder if it has hamilton path or circuit. In hamilton path we have to cross once and only once at an edge, and the start and the finish must be different locations. In hamilton circuit we have to start and finish the same edge. So the circle which B is rounded, which kind of...
  32. jisbon

    Engineering Nodal Analysis of this Circuit using the Laplace Transform

    Was just practicing some problems on the Fundamentals of Electric Circuits, and came across this question. I understand I will have to transform to the s domain circuit, which looks something like this: Then doing nodal analysis, I will get the following for the first segement (10/s-V1)/1 =...
  33. Dor

    !Measuring Currents in a Circuit w/ Semiconductor

    If so, what will I measure in the Ampermeter, the zero total current or the value of the conduction current? I was thinking of the following example- a circuit consist of a current source, an Ampermeter, a switch, and a semiconductor. The semiconductor can have both conduction and displacement...
  34. Const@ntine

    Comp Sci PSPice Lab Exercise - Differentiator (Circuit)

    Look, this is a weird one, but I really need help. This is the Electronics Laboratory, that is supposed to be hands-on, but with Corona it got cancelled. However, they announced that we'd do it through the internet, had us download PSPice, and now we basically have to try and "translate" the...
  35. MARIAM507

    Electric circuit -- Ohm's second law

    I want to know ohm's second law i search many times about it but every time the result is about ohm's first only, so can anyone help me??
  36. tomdodd4598

    I The period-finding circuit for Shor's algorithm

    I've been trying to learn about Shor's algorithm by writing out implementations of the circuit for modular exponentiation, ##{ a }^{ x }\; ({ mod }\; N)##, to find the period ##r## for small numbers such as: ##(N=15,\quad a=11)\quad \longrightarrow \quad r=2##, ##(N=35,\quad a=13)\quad...
  37. S

    [AC Circuit] How do we convert from the time domain to the phasor domain?

    In this example, We need to covert e2 & e5 to a form with imaginary number . we will obtain e2=j10 & e5=20 Can anyone explain how we got this?
  38. S

    Current Induced in one circuit by another circuit

  39. henriquevpp

    Why this Simple Watt Meter for a 220 Volt Circuit works?

    Hello guys! I'm just a begginer student. I found this circuit of a wattmeter that works only with resistors. Can someone explain to me how the 33k resistor give a voltage of 1 mV to 1 Watt? I did not understand why these resistor values has been chosen and why the it measures only in the 33k...
  40. F

    Simulate open circuit and short circuit in MATLAB

    Here's my attempt: The results I got are close to the required answer, but there is a question telling: I tried to solve it, but Isc and Vt (in open circuit) are decreasing with the increase of the field current , so I didn't get the right answer. Could someone let me know where is my...
  41. F

    Engineering Simulate a step-down chopper circuit using LTSpice

    Simulate the circuit shown below sung LTspice.I tried to simulate it , but I didn't get the corrected result. Here's is my attempt: The result (voltage in the collector of the transistor) : Could someone let me know where is my mistake?
  42. dRic2

    I Resonant cavity and circuit analysis

    As I understand, if you solve the Maxwell's field equations for a resonant cavity, supposing a time dependence of the form ##e^{iwt}##, you get an eigenvalue problem and different modes as possible solutions. I'm reading some notes where the author states that each mode can be associated with a...
  43. kellys

    Help with this quantum circuit textbook problem about controlled gates

    Summary:: My skills are very very basic and I'm more a networking major but i had to take a quantum mechanics class, i have trouble with this xcercise from textbook quantum mechanics a general introduction [Mentor Note -- Thread moved from the Technical forums so no Homework Template is shown]...
  44. M

    How to calculate the efficiency of a switch mode power supply?

    I know how to calculate the power output and input by analyzing the current in put and output with multimeters and using the formula P=VI. But P_out is obviously incomparably smaller than P_in so the efficiency would suck this way. Is there a better way to do this??
  45. F

    Simulate a circuit diagram of a step-down chopper using Multisim/MATLAB

    Using Multisim or any Electrical Engineering software: I tried to simulate using Multisim, I got the output voltage. How to find the waveform for the current ? Could someone confirm my answer please? Any help is really appreciated .
  46. F

    Engineering Construct a circuit diagram of a step-up chopper in Multisim

    Using any Electrical Engineering software: I tried to simulate using Multisim, but the output voltage remains constant even after varying R1. Also, I only got the voltage from the oscilloscope, but how to find the current ? Here's my attempt: Any help would be greatly appreciated!
  47. C

    Can I simplify this RLC circuit problem using a different method?

    Hello, I have been thinking about this problem for a few hours, and I do not understand how I should proceed to solve it correctly. Section a is very simple, just substitute in the expression that gives us the values of L and C that the statement gives us. However, when I get to section b, I...
  48. B

    KCL got declined in Norton circuit of an ideal amplifier circuit

    Hi. Let's say we have a circuit like that, and we want to find the Thevenin/Norton circuit from a and b points. So for Vth, we calculate the Voc, in which we remove the 2K ohm resistor and calculate the Voc. I calculated it correctly. But I have problem in calculating the Norton current. So in...
  49. Wrichik Basu

    Electronics How to test whether the circuit board in a UPS still works?

    This UPS has been lying in the house for around seven years. We detached it from our desktop when it failed to provide backup. Six years back, I opened it up and found a swollen battery. At that point of time, I did not have any testing equipment, nor did I have any knowledge of electronics. So...
  50. M

    Two batteries and two resistors circuit - wrong possible answers ?

    It's ABCD question with answers attached. Problem is that, I don't think that neither of those are correct. From KVL the equation seems to be i = (E2-E1)/(2r1+2r2 + R). I've attached images of the circuit, answers, and my solution. Can someone please point me if I am wrong, and if yes, where's...
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