# What is Electrical circuits: Definition and 64 Discussions

An electrical network is an interconnection of electrical components (e.g., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage sources, current sources, resistances, inductances, capacitances). An electrical circuit is a network consisting of a closed loop, giving a return path for the current. Linear electrical networks, a special type consisting only of sources (voltage or current), linear lumped elements (resistors, capacitors, inductors), and linear distributed elements (transmission lines), have the property that signals are linearly superimposable. They are thus more easily analyzed, using powerful frequency domain methods such as Laplace transforms, to determine DC response, AC response, and transient response.
A resistive circuit is a circuit containing only resistors and ideal current and voltage sources. Analysis of resistive circuits is less complicated than analysis of circuits containing capacitors and inductors. If the sources are constant (DC) sources, the result is a DC circuit. The effective resistance and current distribution properties of arbitrary resistor networks can be modeled in terms of their graph measures and geometrical properties.A network that contains active electronic components is known as an electronic circuit. Such networks are generally nonlinear and require more complex design and analysis tools.

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1. ### Is it possible to build a low-voltage Thompson jumping ring apparatus?

Hi all, I'm attempting to build a jumping ring apparatus (a core of iron with the bottom wrapped with wiring like an electromagnet, so that when a metal ring is placed on top of the coil and a current is run through the coil, the ring jumps up into the air). Looking on the internet, I'm seeing a...
2. ### Can someone recommend a relay for me?

I have a 30V - 100A power supply that I want to control using a -/+ 10V NI DAQ. I want a relay between the current output of DAQ and the power supply. Please advise the specification of relay to use. I'd appreciate a comment on how to connect it also.
3. ### Calculating the voltage in an OP-amp circuit with a current source

Summary:: Find the voltage in an OP-amp circuit with current source I(in) = 1 uA. What I'm confused about is if there is any voltage flowing through R1. Because if there was and let's say it went downwards, then where would it go, I mean it cannot just disappear. And if it goes upwards...
4. ### Find the supply voltage of a ladder circuit

Find the supply voltage of a ladder circuit shown, so that I=7A. Assume R=11Ω. (The unit must be placed) Hello, everyone. Please, help me with this. Could someone explain to me how to solve such tasks. I literally spent the whole day watching Khan Academy and trying to figure out how to solve...
5. ### A (very simple) question about terminology in electrical circuits

I am writing tutorials for my students on electrical circuits and I realized that in English I may have been using incorrect terminology (I also teach in French). When I describe circuits, I like to have a term for a section of a circuit that goes from one node to another node and with no...
6. ### Closed vs Open Electrical Circuits

Really coming at this from a radio perspective, where texts refer to closed and open circuits as jargon; never defining. A transmitter sending waves to feed line lacking an antenna = open circuit. Check. A wire of little resistance errantly falling across circuit lines = short or closed...

hello everyone, i have a problem related with sinusoidal steady-state analysis, the problem is like this : the circuit for the question is like this : i am still unable to find the answer for the question (b), the answer i got is not the same as the one provided by the question above, my...
8. ### I On the stability of an LTI circuit

An LTI circuit such as one composed of resistors, capacitors, and inductors, in general is a stable LTI system, i.e. its impulse response is one that decays over time. I have no problem with that, as it speaks for itself through laws of energy conservation, but I want to see this from a...
9. ### Engineering Electrical circuits: when all switches are closed, what is R?

Homework Statement https://pasteboard.co/Hj3g5Km.jpg When both switches 1 and 2 are closed,what is the total resistance of the set up? I couldn't figure out which resistors are connected in parallel and which resistors are actually in series in this set up when both swtiches are closed. I...
10. ### Electrical circuits with resistors and variable voltage sources

Homework Statement The following picture illustrate how the current in the circuit changes when you change ##E_2##. Where slope 1 represents the current flowing through ##E_1## and slope 2 represents the current flowing through ##E2## Homework Equations Usual circuit laws :P The Attempt at...
11. ### Help with two electrical circuits please

Hey, I am having problems with this. I need help with these 2 circuits I am basically lost and not sure how to start. I need to find voltage, current and potency on each resistance help would be much appreciated, thank you http://imgur.com/trm1On0 http://imgur.com/a/KD3zr
12. ### What are the limitations of using electrical circuits to solve PDEs?

Hi everyone. In electrical engineering, when you study control theory, you're taught that electrical circuits can be used to simulate the behaviour of complex systems. What I don't understand is, what are the limitation of this sistem, and why it can't be obviouslly used in a general way to...
13. ### Understanding Electrical Circuits and Power: Questions 10&11

Homework Statement Questions 10&11 in pictures. Homework Equations P=IV W=VIt W=Pt The Attempt at a Solution For 10a) P=IV P=70*14= 980W. 10b) P=IV 1500=12*I I=125A (which is massive so probably wrong) 10c)P=IV 60=I*12 I=5A The 8A fuse because the current flowing through each headlamp should...
14. ### Engineering Electrical Circuits Reactive Networks Question

Homework Statement Homework Equations At low voltage frequency (inductors) L become short circuit and (capacitors) C becomes open circuit At high voltage frequency (inductors) L become open circuit and (capacitors) C becomes short circuit The Attempt at a Solution Part A At low frequency...
15. ### Exploring the Diversity of Natural Electrical Circuits: A Scientific Perspective

Hello everyone, I have a strange question. Can complete electrical circuits be found in nature? If so, can you give any examples? And what is necessarily required (besides electricity) for a complete electrical circuit to occur, naturally or unnaturally?
16. ### Engineering Electrical Circuits - Network/Transfer Function

Homework Statement The Matricial Circuit of a certain circuit in time-domain is: [ -1 D+a] [v1(t)] = [es(s)] [D+2 -1] [v2(t)] [0 ] where a is constant >0. Find G1(s) = V1(s)/Es(s). Put your result in a relation of polinomials N(s)/D(s), with the D(s) monic polinomial...
17. ### Doubts about linear elements of electrical circuits

First doubt: The impedance Z is defined how Z = R + j X and the reactance X can be wrote how: Source: https://en.wikipedia.org/wiki/Electrical_reactance So, by analogy, the admitance Y is defined how Y = G + j B and the susceptance B can be wrote how what? So: B = \left( \frac{\omega C}{1}...
18. ### Engineering Electrical Circuits - Three Phase Power - Y-Y transformer

Homework Statement I took a few pictures of the circuit, it went across two pages so I took a few pictures, and closeups of certain parts to ensure that all the details can be seen For the circuit: http://s7.postimg.org/ywd4nrmsq/IMG_20150905_140403187_HDR.jpg Figure 1. Overview of Circuit...
19. ### Strange questions about electrical circuits

What's up people? I'm new in this wonderful forum. I have several questions about circuits, and they are not really common, I mean, I find them somehow complicated, but I would really come to enlightenment if you guys gave me some clues. 1.- So, let's suppose we got the simplest circuit, a...
20. ### Length contraction test in electrical circuits

As I am sure everyone is aware, there are still folks who don’t believe SRT and GRT. While 99.9% of them are nut-jobs, there is at least one that I respect – Tom Phipps specifically. I am not familiar with any of his writing before the advent of the GPS satellites. In any case, he now accepts...
21. ### Resistors Used in College Electrical Circuits Labs - Any Suggestions?

I am taking an intro electrical circuits course which requires that I write extensive lab reports. I just completed a really simple lab about calculating resistance when configured in series and parallel, etc. In my intro I'm writing a short explanation about resistance, and resistors, and...
22. ### Solving Electrical Circuits: V1 & V2 Equations

Homework Statement Homework Equations 3. The Attempt at a Solution Z11 8 + 6 Z12 6 Z21 6 Z22 6 V1 = Z11 I1 + Z12 I2 V2 = Z21 I1 + Z22 I2
23. ### Writing magnetic monopole analogs for electrical circuits

Homework Statement This isn't a 'homework' problem as such. I'm currently in University Physics II (E&M), and I've become really interested in magnetic monopoles. They haven't been discussed in any kind of depth in my course, but I'm trying to figure out how a magnetic monopole (if they exist)...
24. ### Why isn't my circuit working without both battery terminals connected?

I was thinking, a circuit don't need necessarily be a circuit, can be something like this: How compute the voltage of a circuit if the voltage of the source is different of the sink? Also, how compute the voltage, the current, resistance, etc, of a circuit when we have various sources and...
25. ### Electrical circuits confirmation

Homework Statement Hi, I just need some confirmation on this question on whether it is correct or not. Homework Equations P= V^2/R. Based on that circuit I was asked to complete the following table and then find the power of the circuit. The Attempt at a Solution To find power I did the...
26. ### Physics Lab - Electrical Circuits with Resistors and Capacitors

Homework Statement Hello, I am having trouble with a physics lab report I'm working on. I'm going to try and be as clear as possible. Basically, I'm using different values of R and C in determining tau, the time scale in a circuit's behavior. I used a circuit with a resistor and capacitor and...
27. ### Resistance & Electrical Circuits

Hi, I am massively confused with what resistance is and how it applies to circuits and would be very grateful if someone could help. I know this sounds like a basic question but I have been reading for hours and the more I read the less it makes sense. My book says that resistance is 'the...
28. ### Electrical Circuits - Linear Algebra

Homework Statement Here is a picture of the diagram. http://gyazo.com/f1b7051fda5b9e1d3a185c53abde1211 I must use the Gauss Jordan elimination method and solve for X1, X2 and X3 I am having problems setting up my equations Homework Equations The Attempt at a Solution...
29. ### Engineering Mechanical problems converted into electrical circuits.

Hi, Homework Statement Attached (Q1,Q2) are two mechanical systems I am asked to convert into analogous electrical circuits. In Q2, it was stated that B4 is the friction between each of the three masses and the surface. Homework Equations The Attempt at a Solution Attached (Q1 -...
30. ### The superposition theorem for electrical circuits

Hi fellow physicist! I have some trouble with finding a valid argument, for why the superposition theorem should be fulfilled for electrical circuits - there only containing resistors, capacitors and inductors - where the sources of the emf. are connected in series. Thanks in advance.
31. ### Applying the conservation of energy law to electrical circuits.

Hi guys, I've realized that to truly, deeply, and fully understand something it often helps if you think about the conservation of energy, and then just build up from that. So here I have tried to explain why a battery has a voltage, and why there are voltage drops across resistances...
32. ### Design a Capacitor for Electrical Circuits: Given Power, Time, Voltage

Given the power that is needed to be output by the capacitor - P the length of time that the capictor must give off that power - t the maximum operation voltage that the capacitor can operate at- V the dialectric constant of several materials - ε the breakdown field of those several...
33. ### Thermal Noise in Electrical Circuits

Dear people, it might be a simple question, but I have been on this for over 2 days now and can't find a proper explanation of this anywhere: https://dl.dropbox.com/u/2264519/circuit.jpg Picture a RCL circuit which is kept at room temperature. Now even when there is no current going through...
34. ### Calculating Voltage Gain for Electrical Circuits

Homework Statement I've been reviewing my electrical theory and I'm having trouble trying to calculate an expression for the voltage gain for these two specific circuits. (Images c and d of the question.png attachment). I already know the answers, however I am unable to derive the same...
35. ### Tricky wording in electrical circuits question

Homework Statement Homework Equations The Attempt at a Solution When it says, without changing the circuit, does it mean adding something else that is extra or does that mean i have to solve it without closing the switch?
36. ### Electrical Circuits 1 and Electrical Circuits 2

What exactly do they teach in these classes? My second year I will be taking these classes, heard these are some hard classes. Anyone on this forum ever taken these classes?
37. ### Engineering Matrix therory - Electrical Circuits

Theoretic question: is there a way to know if it is no possible to write impedance/admitance matrix (depend on which method we want - volage or currents) just from the circuite connections? Thanks!
38. ### Engineering Find Thevinin Equivalent for AB - Electrical Circuits Homework

Homework Statement I need to find the thevinin equivalent for points AB. The Attempt at a Solution I know the Is current is splitting equally between R1 and R3, but doesn't go to R2 because of the dependent current source. so i thought that through: I(R5) = Is and I(R3)=Is/2 so the...
39. ### Engineering Electrical Circuits: Frequency Generator, Tolerance & Reactive Inductor

Homework Statement 1. How do you expect the frequency generator output voltage to change with increasing load (decreasing impedance)? 2. Explain the meaning of component tolerance. (E.g. Tolerance of a resistor) 3. Is a real inductor completely reactive? Why Homework Equations...
40. ### Engineering Solving Electrical Circuits: Find Voltage Vx

Homework Statement I need to find the voltage Vx. Vs = V0*cos(wt) given: w,R,C,L,V0 I thought doing KVL,KCL but got stuck... is this the way to solve this? is there another way? Thanks!
41. ### Complex analysis in electrical circuits

When discussing the i (the imaginary unit) in a math class, my math teacher commented that that complex analysis is used in studying electrical circuits. I know a little about resistors and what not, but never have I seen complex analysis used this way. I've tried looking it up, but it's been...
42. ### Exploring Superposition in Electrical Circuits: What is i3?

Hello! If we want to find i3, we can apply the superposition theorem to the circuit below. It gives For V2 set to 0: i3' = V1 / R1 For V1 set to 0: i3'' = V2 / (R1 || R2) i3 = i3' - i3'' = V1/R1 - V2 / (R1 || R2) i3 = 10 / 500 - 2.5 / 83.3 = -0.01A My question is Do the i3' and i3''...
43. ### Electrical Circuits - Find the power and Voltage

Homework Statement [PLAIN]http://img143.imageshack.us/img143/3746/electriccircuits.png Homework Equations The Attempt at a Solution Can someone help me with part B of this? I understand that in part a it says the 5 A source is delivering 10 W of power, so that would in turn...
44. ### Grounding in electrical circuits

I feel as if the difference between grounding in a circuit and grounding in mains power is not very clear. So my questions are, what does a ground do in circuits and is it necessary?
45. ### Electrical circuits don't flow in a circle?

So I came across http://amasci.com/miscon/eleca.html#circle" on W Beaty's site and it's not sitting well with me. Here is a quote: This doesn't seem right to me. My impression has always been that the charges flow from one of the slots (hot) in the wall socket and return on the other...
46. ### Polarities issue in electrical circuits

Hi everybody... I have a question in the electrical circuits .. When i combine two resistors ,either they are in series or in parallel .. Is there any constrain to put the polarities ?
47. ### Measuring Energy of Transients in electrical circuits

Hi, Is there a way or reasonably priced equipment out there that can measure the energy levels of transients in electrical circuits? Any help would be appriciated!
48. ### What is the purpose of resistors in electrical circuits?

I looked this up, and found that it limits the current going through, but say if we have a c ircuit with a power source and 1 resistor, the current through the resistor is the current coming out of the resistor. I know if you hook the resistor up in parallel that is not the case, but in some...
49. ### Questions About Magnetism Interfering With Electrical Circuits

It would be appreciated if formulas that would directly or indirectly allow the following quantities in question to be calculated are posted in this thread. The questions are listed below: 1.) How strong would a magnetic field have to be to block a given amount of electric power in a given...
50. ### An electrical circuits problem involving integrals, all rules given, tell me if right

Homework Statement A voltage of 60cos(4 \pi t) V appears across the terminals of a 3mF (milli-farad) capacitor. (which is equal to .003 F [farad]). Calculate the current through the capacitor and the energy stored in it from t=0 to t=.125 s Homework Equations Current through an ideal...