# Electric circuit Definition and 51 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. ### Am vs Fm variable capacitor receiver, what is the difference?

What is the difference between a variable capacitor in a AM receiver and a variable capacitor in a FM receiver? I understand that Am is amplitude modulation and that the signal is carried over a changing amplitude and that the frequency is constant. And the opposite in FM signals. And a variable...
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.

4. ### 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.

6. ### "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...

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8. ### 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?
9. ### 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
10. ### 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...
11. ### 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...
12. ### 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...
13. ### 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...
14. ### 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
15. ### 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...
16. ### 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...
17. ### 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...
18. ### Circuit problem

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...
19. ### 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...
20. ### Which way do I measure the potential difference

Homework Statement All the bulbs in the circuits are identical, as are all the batteries. Rank the magnitude of the potential difference between points M and N. Homework Equations V=IR The Attempt at a Solution My most fundamental question is actually which way do I know to take the...
21. ### What's the current from this circuit? Is it a short circuit or not?

Homework Statement Pic A, what's the I2? Pic B, what's the current across a-b ? Homework Equations V = I*R Voltage in series is different, the current is the same Current in parallel is different, the voltage is the same The Attempt at a Solution from Pic A, I found that I1 = 1A, I3 = 1A...
22. ### Find the current I in this electrical circuit

Homework Statement Homework Equations V = I.R The Attempt at a Solution 6 ohm and 3 ohm are series = b Then b pararel to 9ohm = c = total resistance b = 9ohm c = 9/2 ohm I = V/R I = 9.6/c I = 2,13 A Can you help me? Is it right? My friend's answer is 0,8
23. ### Using Kirchoff's Voltage Rule to find currents in a system

Homework Statement Then solve these equations for i1-4 Homework Equations V=IR The Attempt at a Solution 80i_1-50i_2-30i_3 = -120 -50i_1+100i_2-10i_3-25i_4 = 0. -30i_1-10i_2+65i_3-20i_4 = 0. -25i_2-20i_3+100i_4 = 0. i_1=-4.18239492 i_2=-2.66455194 i_3=-2.71213323 i_4=-1.20856463...
24. ### Engineering Find Currents I1 and I2 in an Electric Circuit

Homework Statement I need to find the currents I1 and I2 in the attached image, but am having some difficulties grasping the concepts. I am given E(t) = 338sin(t) as well as values for R, L and C. I think I know what I need to use but I am not sure how to put it all together Homework Equations...
25. S

### I Does chaos exist in circuits with linear elements?

I have heard that chaos exists in all dynamical systems.Does this mean that chaos exists in circuits with linear elements too?Which software is best for analyzing chaos in electric circuits?
26. ### How do solar cells generate current from pn-junctions?

Looking for a practical description. I have a feeling I am grossly misunderstanding something fundamental about electric circuits and apologize if my questions are confusing because of it. I have these two sources: acs hyperphysics My (probably naive) understanding of the process is as...
27. ### Calculate resistance if the switch is closed 2 battery with different voltage

Homework Statement before that, can you tell me about "current flow in this circuit" if : A. the switch is open B. the switch is closed the Question is No. 1 Calculate the resistance of R if the value of the current I in the figure is 0.50 A. ( i think it is related to no 2) no 2...
28. ### A Conductivity change of a tank (glass coating on steel)

Suppose I have a tank which is made of steel coated with a thin layer of glass on the inside to protect the steel from corrosion (the material stored inside the tank is corrossive; say for arguments sake Water with 10% Hydochloric Acid). In theory, till the glass is intact there is an...
29. ### Elektrical and kinetic energy

I got a question towards kinetic energy and elektrical energy. They always talk about about particle accelerators or devices when talking about transformation of elektrical energy into kinetic energy of elektrons. But do elektrons also have kinetic energy when they are circulating in an...
30. ### Charging of a battery

A battery has an Emf 6 Volts. It is completely discharged. It is charged by maintaining a potential difference of 9 Volts across it. If the internal resistance of the discharged battery is 10 ohms, find the current through the battery, just after the connections are made. My textbook says that...
31. ### Power Supply Problems

Hi! I'm trying to build a variable voltage DC regulated power supply that is 0-30v and 2mA-3A. The problem I'm having is that as soon as I plug it into get a reading on my multimeter it reads 34v, even if I try turning the pot it does not change. I've rewired the pots and made sure the...
32. ### Circuit settles to steady state and switch is opened

Homework Statement The circuit consists of three identical light bulbs and two identical coils, connected to a DC current source. The ohmic resistance of the coils is negligible. The system is left to settle into a steady state and then the switch S is opened. Describe and explain in as much...
33. ### Find the equivalent resistance between AB

Homework Statement Find the equivalent resistance between AB. Homework Equations The Attempt at a Solution I could not find any Wheatstone bridge or series parallel combination. Should I use star delta transformation ? If yes, how exactly should I use it ?
34. ### How to calculate the equivalent resistance using wye delta ?

Homework Statement https://z-1-scontent-sin1-1.xx.fbcdn.net/hphotos-xtf1/v/t34.0-12/12435980_942112312550457_1708451532_n.jpg?oh=b29a5e9b2ff96bbf0e11932d081eb25e&oe=568A9B79 [/B] We need to find the equivalent resistance along A to B ie AB Homework Equations R=(1/R1 + 1/R2+...+1/Rn)^-1 ...
35. ### Physics Olympiad question Electric circuit

Homework Statement In the Circuit(pic attached) the following resistor combination is found. All the resistrs in the figure has resistance R ohms. What is the total resistance across AB? Homework Equations V=IR 3. The attempt at a Solution between point A and B there is only one resistor so i...
36. ### How do i interpret the following electric potential diagram?

We recently started to learn about electricity in school and I'm trying to understand the concept of voltage(potential differance). From what i understand, electrons flow from the negative terminal to the positive. The electrons at the negative terminal will have 1.5 J of potential energy per...
37. ### Help understanding the Voltage in a circuit.

What is voltage in a circuit? We just started learning about electricity in my school. From what I understand; potential is potential energy per Coulomb and voltage means difference in potential. So, if you have a battery with 4 voltage and a wire connecting the poles of the battery, does that...
38. ### How does surface capacitive touchscreen work in detail?

It's pretty easy to find the "working principle" of surface capacitive touchscreen like http://www.elotouch.com/Technologies/SurfaceCapacitive/howitworks.asp [Broken] Roughly speaking, I know that A surface capacitive touchscreen has a conductive layer to which some electrodes are attached...
39. ### Electric Circuit With An Electric Motor - Satellite Project

I am a software engineering major, and I am having some trouble with an electric circuit in my satellite project. Basically I am trying to generate 1G on the inner surface of a cylinder with a radius of 0.03m, connected to an electric motor which has to rotate at about 173 rpm (to generate 1G...
40. ### Power dissipation in capacitor circuit

Capacitor connected to a battery of certain internal resistance. If it is asked to calculate what is power dissipated as heat, Does -the voltage across capacitor X current through capacitor- gives heat dissipated or should we add heat dissipated in battery by considering its internal resistance.
41. ### Capacitor in a circuit

We know that - VM=VCl - R1=1000.0 Ω - IM=0 - VNa=61 mV - VK=-88 mV - VCl=-71 mV Question is: what is R2? I've written according to Kirchhoff's second law that (1) VM + VNa - R1INa = 0 and (2) VM - VK - R2IK = 0. We can also calculate that ICl=0. With these equations and according to...
42. ### Engineering Parallel circuit problem

Homework Statement Solve the next circuit to find the voltages Homework Equations I=V/R GT=(1/R1)+(1/Rn) V=V1=V2=V3 The Attempt at a Solution My background is that I know that in a parallel circuit, the voltage for each component is the same and electric current it's equal to the sum of the...
43. ### Power Factor of an L-C-R curcuit

Homework Statement A series L-C-R circuit Comprises of a 250mH coil, 0.01 MFD capacitor and a 5W resistor. A dependent voltage defined by e = 2.5cos(80000t) is applied across it. Determine the power factor. [/B] Homework Equations Power Factor = cos(x) = R/Z Z = sqrt^[R^2 + (XL - XC)^2] The...
44. ### How to make a delta function signal in a circuit?

Basically I want to test my analog circuit using a forcing function that has a form of a delta function. The function generator I use outputs sine wave, triangular wave and square wave (+ve and -ve output in one period). Are there any ways to produce a square wave that has an output for like 5%...
45. ### What does 0 V exactly mean in an electric circuit mean?

I'm a mechatronics engineering student, and I know that electronics is a requirement in most engineering programs. I'm been dealing with electronics recently and I've been studying electric circuits. I've been noticing that in some of them instead of being closed (in diagrams) they are like...
46. ### Does a moving magnetic field generate a current?

Hey! Not sure if this is a stupid question or not but I was wondering if a moving magnetic field could generate a current in a wire. I know that moving a wire through a magnetic field creates a current but what if you move around a magnet underneath a circular wire. Does that generate a current?
47. ### Capacitors and a Switch

Homework Statement The switch is initially open and the capacitors are uncharged. The applied potential difference Vab = +210V. a.) What is the potential difference Vcd? b.) What is the potential difference across each capacitor when the switch is closed? c.) How much charge flowed through the...
48. ### Potential difference across two points in a circuit

Homework Statement [/B] Find the potential difference between points b and a in the circuit below I have already solved for the voltages of the two batteries (1 and 2) in the circuit (18 V and 7 V respectively) 2. Homework Equations Kirchhoff's Rules 1) Potential difference across any...
49. ### Magnet/Electricity to rotate object 90 degrees?

Hello, I want to create a motion using electricity, using the cheapest means possible (DIY). Basically I'm trying to rotate an object 90degrees when the current is on, and back to its original position when the current is off. The questions are: 1) Is this possible? 2) Can this be done using...
50. ### Wye-Delta transformation

To prove the wye-delta transformation formula, it is said 'If the two circuits are to be equivalent, the total resistance between any two terminals must be the same.' But why ? I can't convince myself that it is sufficient condition for the equivalence of circuits.