What is Electric circuit: Definition and 201 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. Electric field around a circuit

We know that E is conservative so the integral of E around a closed loop is zero. I know this helps us (in some way, that's why i'm asking) to calculate the total voltage drop around the complete circuit (which is zero). What exactly is "E" in the integral? For example, internet says "electric...
2. B Found a circuit where current is zero across an ohmic device (dV>0)

I know that a voltage difference doesn't necessarily imply current flow, but all the explanations I seem to find of that either say that that happens because the resistance is infinite, or there is nothing connecting the two points in question (the two are basically the same thing, as I...
3. Circuit with potential difference across battery being zero?

Using KVL we have ##\epsilon_1-\epsilon_2+iR=0##. It seems that ##\epsilon_1,\epsilon_2##, and ##R## are given and the only variable is ##i##. Thus, ##i=\frac{\epsilon_2-\epsilon_1}{R}## for the KVL equation to be true. However, it seems like when we think about what happens to this circuit...
4. Why does amplifier sink power for Vout>0 and sources power for Vout<0?

TL;DR Summary: How do we show that the dependent current source in a single-stage amplifier sinks power for ##v_{\text{out}}>0## and sources power for ##v_{\text{out}}<0## I am trying to solve a problem set from MIT OpenCourseWare's 6.002 "Circuits and Electronics" course. There is a problem...

20. I Energy of an electron in an electric circuit

When an electron flows through a circuit say 250V, does it mean the electron possesses 250eV at any time or does it give out a total of 250eV
21. I Why in an electric circuit with only a generator the resistance R=infinity?

Why in an electric circuit with only a generator the resistance R=infinity? [Newbie's post edited by a Mentor to delete extraneous embellishment]

23. Engineering Finding V and I in a simple circuit

So I know I have to use kirchhoff's Voltage Law so when I apply it's: -12+4i+2Vo-4-Vo=0 and Vo=6i so --> -16+4i+2(6i)-(6i)=0 but apparently that's wrong and Vo should be =-6i and so when I substitute it in the equation it should be -16+4i+2(-6i)-(-6i)=0 and I don't understand why.

25. "Barlow's wheel" used as an electrical generator

In this thread, I hope to find some help in understanding one of the first application of Faraday's law of induction: the "Barlow's wheel". Basically the machine converts electrical power to mechanical, so as you can imagine, a battery, some conductor wires, a horseshoe magnet and a metal wheel...

27. Electric Circuit Analysis, Nodal Analysis and finding Voltage.

Summary:: The image shows two circuits, in the first one, using Nodal Analysis we find that V1=4.8V, but in the second circuit V1=10 because using KCL - 10+V1=0. I understand what happened in the first circuit, but I don't understand what happened in the second one, they look the same to me...

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29. Help finding Thevenim Equivalent - Circuit Analysis

Summary:: So I found Vth=1.19 using Nodal analysis and I'm not sure if that's right, I'm trying to find Rth now but I'm confused as to what to do, any tip that tells me at least from where to start is appreciated. Edit: so I did 12||60 so Rth=10 ohm, is that correct? Is Vth correct too?
30. Finding a good descriptive model of the electric circuit (for 8th graders)

Since this quesstion popped up in this thread I thought it might be better to create a new thread: https://www.physicsforums.com/threads/a-question-about-an-electrons-movement-in-a-dc-circuit.997736/ The question is the following: What kind of descriptive model could/should one use while first...
31. Power Calculation of general electric circuit

I am trying to calculate the power calculation of a general circuit with voltage leading the current by a phase difference of ##\theta##. The instantaneous voltage is given by ##v = V_m\sin(\omega t +\theta) ; i = I_m\sin(\omega t) ##. The instantaneous power is then ##p = V_m I_m \sin(\omega t...
32. Electric Circuit: Path of Least Resistance

I figured that when you close the switch the current from the upper cell will travel through the closed switch due to it being the path of least resistance, essentially the resistor between cells is unused (was my first thought). I'm not entirely sure how to progress with this question.
33. Electric Circuit Differential equation help

I'm confused at the part how 4Vc and 48 cos(60t) are deduced, that's all.
34. Could you check this Li-ion charging circuit?

Can secondary cell can be described in circuit simulator?? With other symbols like capacitor. Also I wonder if there's a program that provide secondary cell(like Li-ion battery). Please help me
35. 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
36. 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...
37. 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??
38. 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...
39. 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.
40. When a short-circuit exists, how to find the current?

I am not an English speaker, I apologize that I cannot use English well. I have a question calculating the IN. When the terminal a-b is short-circuited, is it right that the currents are zero at 2 ohm and 6 ohm resistances?(Because they are parallel with a short-circuit.) Also, because the...
41. How to find the equivalent resistance of this electric circuit?

Summary: How to find equivalent resistance of the electric circuit? I need to solve the following problem: Calculate equivalent resistance of the circuit (figure1), if all six resistances are the same: r1 = r2 = r3 = r4 = r5 = r6 = 100 Ohm. True answer: 66.6 Ohm. I tried to solve this...
42. Determine the capacitor value so that this circuit is in resonance

L=100mh=0.1H ω=10^3 rad/s -> f = 159Hz XL= ωL= 2πfL= 2π*159*0.1= 99.90 Ω Z parallel = [(XL∠90º)*R2] / [(XL∠90º)-R2]= 37.13∠-21.8º XC= 1/ωC= 1/(2 π f C) I don't see how I am supposed to get to C
43. Electric field in a circuit with a DC source

So I understand that when an electric field is produced in a conductor of length L, the net electric field in the conductor will be 0 because the rearrangement of electrons in the conductor results in the production of its own electric field which cancels out the one produced initially...
44. Draw an electric circuit potential graph

Hi. I have physics homework that I don't understand. Hopefully, someone here can give me some advice. So, the homework goes like this: Draw an electric circuit potential graph and find out the potential difference between points B and C. The two resistors have equal values. Believe me or...
45. Engineering An electric bulb of 500 W at 100v is used in a circuit

If the circuit has 200 V supply. The resistance R that must be put in series with bulb so that it draws 500 w is? 2. Relevent equations P= v^2/r I = v/r 3. My attempt at the solution R= V^2/P r (bulb)= 10000/500 = 20 ohm Now for 200 v supply .. P= 500 W V= 200V Rnet = 20 + R R+20= 80 R= 60...
46. How to fix this electric circuit

Homework Statement I'm not sure if the construction of this circuit is correct, so that both lamps, which are the same, shine equally brightly. Otherwise only the resistors are given. If it's wrong, what else would it look like? And why?[/B] Homework Equations I guess the laws of Kirchoff...
47. Basic question about current in an electric circuit

Let's say we have a basic electric circuit consisting of a battery with some potential difference, and a loop of wire. The wire loop also has some segment with a higher resistance. Now since there is a potential difference, the free electrons will move to make the circuit equipotential. The...
48. Circuit problem involving sources and resistors

Homework Statement The currents ##I_{{a}}## and ##I_{{b}}## of the circuit have values 4A and -2A in that respective order. A) Find ##I_{{g}}## B) Find the power dissipated by each resistance C) Find ##V_{{g}}## (voltage drop across the current source) D) Show that the power delivered by the...
49. Untangling a Confusing Circuit: Solving Kirchoff's DC Laws

Homework Statement It’s a rather confusing circuit, I’m having problems trying to understand the way current circulates through the circuit. Homework Equations Kirchoff’s DC circuits laws only, no resistive simplification neither nodal analysis The Attempt at a Solution I’ll attach my intent...
50. Electrical Component with the Letter M?

1. Homework Statement This is the sample answer to the circuit they ask to draw. I get the comparators, the inverter and the Gate. That’s all clear. Then they wanted a switch that needs to be used to end the sound alarm, regardless of comparator output. I assume this the box labelled M...