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Questions tagged [electric-circuits]

An electronic system, with closed loop current flow, and relative electrical potentials present across electrical components.

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Flux operator and phase operator in Cooper pair box

An isolated Cooper pair box is equivalent to a capacitor in parallel with a non-linear inductance and its hamiltonian is equal to $$H = 4E_C \hat{n}^2 -E_J \cos{\hat\varphi}$$ In particular, $E_C = \...
Ric's user avatar
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Current through points with no voltage drop

I've had a problem with switches in between parallel circuits. In this textbook question: The answers state "Note that there is no voltage drop across the voltmeter". However, there is a ...
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Proof of concept of symmetry for circuits [closed]

In my textbook the method of symmetry for solving complicated symmetrical circuits . I have the intuition of why the idea of symmetry works but I’m unable to prove it mathematically using Kirchoff’s ...
LuminoYB's user avatar
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How to count simple resistor circuit configurations? [closed]

Really stumped by this one (I'm not an EE!). Suppose we are given 1, 2, 3, 4, 5, and 6 one-ohm resistors. They can be arranged in series, parallel, bridge, and so forth circuits. No dangling resistors ...
Ken Bannister's user avatar
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What happens to the charges in an inductor when you induce a voltage?

Say you have two inductors, and - very much like a transformer - you connect the first one to a voltage source, then place the other one close to it, so that there will be an emf induced by the change ...
cabutchei's user avatar
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Voltage biased Josephson junction

Consider a pure Josephson element (i.e. a Josephson junction, whose capacitive behaviour is neglected). The hamiltonian of an isolated Josephson element is $$H_T = -E_J \cos \hat \varphi$$ Now, ...
Ric's user avatar
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Is my simplified explanation of Volts vs Current correct? [closed]

I was struggling to find any meaningful difference between Volts and Current, when studying the basics of Ohm's law. The sentences explaining Potential Difference, between the negative and positive ...
securityauditor's user avatar
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Charging a capacitor without closing a circuit

It might sound absurd but is it possible to charge a capacitor solely by connecting the positive terminal of a battery to one plate of the capacitor and the negative terminal of another identical ...
Nightwing's user avatar
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Powerlines in Asian villages are they safe? [closed]

Powerlines in Asia - I have seen lots of lines wound up or passing through bushes. Is this dangerous? How does this work?
Diatom's user avatar
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Circuit quantization procedure

In circuit QED, we construct the hamiltonian of a circuit following Devoret's procedure. We start from a classical treatment, in which we impose Kirchhoff's voltage laws on fundamental loops and ...
Ric's user avatar
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Battery in non-closed circuit with charged body and Earth

Looking at the clips on how the battery works, I understand that eventually one of the ends releases the electrons which then move through the conductor to the other end, to continue the reaction. Now ...
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Why electric field increase near the cable connected in AC 220V socket even current is zero?

If I put low frequency electric field meter near the connected cable in AC 220V socket, he show 1200 V/m even if device is turn OFF(zero current), if disconnect cable from socket, field drop to 8 V/m. ...
22flower's user avatar
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Why do lamps in circuit have potential difference but two points in cable without anything in the middle of it have no potential difference?

I'm preparing for my EE major, this is my starting point.
Raudana Muntazar's user avatar
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3 answers
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Visualization of resistance [closed]

What does a resistor do in an electrical circuit? Does it impede the flow of electrons by increasing offering a path that offers a large no. of collisions? How can i visualise it, i have been told to ...
Anton Bert's user avatar
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Confusing definitions of EMF

I was studying about EMF (electromotive force) recently but had trouble connecting the two definitions of the topic. Here are the two definitions of EMF listed in my book (The book I've referred is: ...
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Why is my idea of voltage drop wrong?

when battery is connected to 2 ends of a wire, potential difference is created, this causes electric field causing electrons to move, the field gives the electron electric potential and the thus ...
Anton Bert's user avatar
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How can I deduce a capacitance of a capacitor without existing formulaes?

Understanding Charge Accumulation in Capacitors Connected in Series I've been exploring the behavior of capacitors connected in series and developing a conceptual model to understand how charge ...
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Doubts in circuit analysis [closed]

I am really confused here how is the potential at O found? Resistance is equal at all resistors this is an illustration in my book, they have not explained why voltage at O is 50V, just stated that ...
Anton Bert's user avatar
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Volume distribution of charge in a wire in a DC circuit

According to this and several other articles some amount of charge in a DC circuit distributes itself on the surface of the conductor, making the electric field inside parallel to the said surface. ...
user567_9's user avatar
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1 answer
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How do conductors actually work in electrostatics? [closed]

I am mainly confused because we are learning about conductors in electrostatics, and I always think of an electric wire connected to a phone charging it (a phone charger). So, when I hear "...
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Confusion regarding phase

As far as I know about phase if the phase difference between two waves is positive, the former is leading..and the latter is lagging. Then why has D J Grifith stated this? If the phase of the magnetic ...
Suhail Sarwar's user avatar
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Working of batteries and supply of charges through them when connected to capacitors

My doubt is not really related to capacitance but about the fundamentals of working of a battery. A capacitor with certain capacitance is charged as shown in the figure. Please note that battery is ...
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Weird looking sine wave behavior in an electric circuit

while studying an RLC circuit I noticed some weird like sine waves at low frequencies (1-9 kHertz) on the inductor, The amplitude behavior did not follow the theoretical model. Instead, suggested the ...
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Cannot catch a minus sign mistake when deriving the ODE for an LC circuit

It's probably a very basic question but I just cannot wrap my mind around it. I'll just try to derive the differential equation for an LC circuit: According to the law of induction, in a solenoid we ...
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To find the equivalent resistance between points A and B in the circuit [duplicate]

The question is to find equivalent resistance between A and B. My teacher solved it by marking equipotential points and modifying the circuit as shown below Clearly, as per the modified circuit, the ...
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Potential difference when two emf sources are connected in a simple loop circuit

I am having difficulty understanding the equation below for the potential difference between the two terminals of an electromotive source when two sources are connected from Sear and Zemansky's ...
nomadicmathematician's user avatar
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Why is induced EMF in DC motor being included in Kirchoff's Loop Rule

I was reading some lecture notes (don't think I can include them here) that show the EMF induced in the armature of a DC motor, being included in the equation of Kirchoff's Voltage Law for the ...
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Determining voltage on branches with current sources in DC circuits using [closed]

I have a task on electric circuit theory where I need to find all currents flowing through the branches and corresponding voltages. To solve this problem, we need to use loop current method. The main ...
Dmitry Finogenov's user avatar
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2 answers
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Do we have to provide energy to move electrons in an electric field?

In the positive and negative terminal of a battery, there is potential difference due to the accumulation of charges in their respective terminal, so it created a potential difference, and if we ...
Nishesh Tyagi's user avatar
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1 answer
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Current flow on the edge dodecahedron [closed]

What is the method for solving this kind of problems? In this dodecahedron (30 edges) identical resistors are placed along all the edges. What is the current flowing through the edge AB?
Galaxy Inc's user avatar
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How to solve the transient response of a general $RLC$ network?

There is a $RLC$ network $\{V_i\}$ with a complex impedance $Z_{ij}$ on each edge. all vertices have initial voltage $V_i$ and all edges have initial current $I_{ij}$. Now, is there a general way to ...
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Can resistors having equal magnitudes of potential difference be considered to be in parallel?

More specifically, if potential difference across a resistor, is exactly negative of the potential difference across another resistor, can they be considered to be in parallel? If so, why? Can the ...
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What exactly is equivalent resistance?

We all know the basic example of school with series and parallel resistors, so they might be a good place to start. Given two terminals $A$ and $B$ from a circuit, if the current that exists $A$ is ...
hellofriends's user avatar
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Can A rod in a magnetic field be equivalent to a circuit component?

Consider the rod in a circuit with current $i$, then the force is $$F=BiL$$ the mass is $m$ and the velocity is $v$, then $$F=m \dot{v}$$ $$E=BLv$$ then $$i=\frac{m}{B^2L^2}\dot{E}$$ This seems like ...
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In an infinite square grid of resistors, why isn't current distributed equally at adjacent node of current injection?

Consider an infinite square grid of resistors, where a current of magnitude $i$ is injected at a particular node, and withdrawn at infinity. At that node, the current would split equally in the four ...
brainfreeze's user avatar
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Voltage drop across an ideal inductor

I was afraid to type the title of the question though there are lot of answers to similar questions. I spent half a day going reading these questions and trying to understand the answers posted and ...
Vinay5101's user avatar
1 vote
2 answers
91 views

Calculating equivalent resistance of a beautifully "symmetric" circuit [closed]

In the given circuit, we have to find the resistances between A and B. I like to solve such problems by first finding out points which are equipotential, as resistors between such points are ...
Bongo Man's user avatar
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Inductors with different directions connected in series

I know that inductors oppose the change of the current. So for two inductors with different direction in series (one in clockwise and the other in counterclockwise), the equivalent inductor is $L_{eq} ...
Jarry's user avatar
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6 answers
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What is electromotive force? What's its relationship to Voltage? + clarification of confusion

So first of all, yeah I know that the electromotive force is not a force (the name was coined by Alessandro Volta I think). About Power and dissipated power The power with wich a battery provides the ...
Manuel's user avatar
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Does all the Energy provided by the battery dissipate into heat?

Before proceeding onwards please note that I am talking about a simple circuit consisting of an ideal battery, a switch and an external resistance. So I was told that $$ W_\text {ideal battery} = Q_\...
Gauransh's user avatar
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How can red LEDs still give a faint glow at a voltage of only 1.4V? [duplicate]

How can a red LED work at a voltage of only $1.4{\rm V}$? Red photons have an energy of $1.77{\rm V}$ if we use $\lambda = 0.7\mu\text{m}$ in the relation: $$ E = \hbar \omega = \frac{2\pi\hbar c}{\...
Jos Bergervoet's user avatar
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0 answers
70 views

Why does this RLC behavior differ from what equations predict?

In order to better understand RLC behavior under current sources, I constructed the simple circuit below and attempted to analyze it. However, my equations do not agree with simulation results. The ...
SRobertJames's user avatar
2 votes
0 answers
114 views

What are the limitations of Nodal Analysis?

Yea, that's the question basically. What are the limitations of Nodal Analysis? Like, for example take the following case, we have to find out the net capacitance between A and B. Now I want to solve ...
Adhway's user avatar
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Is it safe to assume it to be a balanced Wheatstone bridge?

If we calculate the potential at both ends of these $3\,\Omega$ and $4\,\Omega$ resistors, that comes out to be the same. It is $V/3$ at both ends of the $3\,\Omega$ resistor and $2V/3$ at both ends ...
Physics_enthus's user avatar
2 votes
1 answer
45 views

A-Level physics question: gradient of graph of voltage [closed]

I am trying to do question 25(b) from this A-Level physics paper: (page 20/28) https://ocr.org.uk/Images/677416-question-paper-breadth-in-physics.pdf According to the mark scheme, the graph should be ...
Oliver's user avatar
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1 answer
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Current equation for a circuit containing 5 basic elements in series

Does a general equation (for current) exist for a circuit containing the five elements namely e(dc), e(ac), R, L (active/inactive), C (charged/uncharged) in series? If yes, can i derive from it the ...
KPS's user avatar
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0 answers
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Current sensitivity in transformer scheme with SQUID

I've tried to determine the maximum current sensitivity in this transformer scheme but I'm not sure if my solution is valid. I need to find the relation between the current in the input transformer ...
Anton Gunnarsson's user avatar
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2 answers
65 views

How to find current direction from voltage value?

+2024.06.04. editted I'm adding an example image of the data I have. My circuit is a raster(matrix) format, and each cell (entry) is a node of the circuit. In the example, 1A is injected into the ...
Non's user avatar
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2 answers
103 views

Charge on parallel plate capacitor before and after connecting battery

Suppose we have two plates which have unequal magnitudes of charge. When we connect these plates to a battery, why does the charge on both plates become equal and opposite? Why is capacitance defined ...
user1188500's user avatar
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1 answer
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Why does the current increase in this circuit?

I have understood the later parts of the model answer, but why does the current increase? I know that the brightness of a lamp is determined by its power which is given by $P=IV$. Since the current ...
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