Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [electric-circuits]

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

-4
votes
1answer
73 views

Question about circuit with two cells [closed]

Edited - could someone explain how you treat a circuit with two cells in respect to circuit laws and also whether the section in the middle is in parallel or in series. Second Edit: I’ve researched ...
-1
votes
1answer
25 views

The flow of electric current

If positive charges have higher electric potential difference than negative charges then why the negative charges (electrons) are the one that are moving in a circuit? and to my knowledge the ...
-1
votes
0answers
28 views

Book on heat generated in a circuit

Can someone suggest me a book with tough quality questions on heat generated in a circuit like in rc,lr circuits etc.
0
votes
4answers
99 views

How to understand Kirchhoff's Voltage Law?

I'm having a hard time trying to understand why Kirchhoff's Voltage Law is true. I looked for an answer on the forum but I couldn't find a convincing one. So my question is : How to "physically" ...
2
votes
2answers
113 views

Now what will happen in this circuit?

Consider a circuit as shown in this figure below- Assuming switch S1 is closed such that current flows in loop ABCDE for a long time and steady state is reached. Now, my question is simple, suppose (...
1
vote
1answer
43 views

Why is a parallel RLC circuit usually driven by a current source?

Almost always when I see an example of a parallel RLC/LC circuit diagram online, the circuit is driven by a current source instead of a voltage source. On the other hand, the series RLC is always ...
20
votes
9answers
6k views

The water analogy seems to imply that power = current. Why is this incorrect?

Many people think of the water analogy to try to explain how electromagnetic energy is delivered to a device in a circuit. Using that analogy, in a DC circuit, one could imagine the power-consuming ...
2
votes
2answers
34 views

The electric field between two plates of a capacitor

Suppose you a have a parallel plate capacitor connected to a battery of voltage $V$, and charge is starting to accumulate on the side of the capacitor connected to the positive end of the battery. ...
0
votes
4answers
73 views

How is energy conserved in a theoretical circuit where you put a lightbulb and two rechargeable batteries like… (diagram included)

In the beginning the first battery is fully charged, and the second is fully discharged. As the circuit is connected the discharging battery recharges a dead second battery and light is emitted from ...
0
votes
2answers
30 views

Why is the integration constant in a purely inductive AC circuit assumed to be zero?

While studying about AC circuits, I came across the usual differential equation of an AC circuit (in which the voltage across the source is a sinusoidal function of time) containing an inductor only. ...
0
votes
3answers
126 views

Current in infinitely long wire? [closed]

Theoretically, suppose an infinite-length wire with completely no resistance (0Ω) connected to the terminals of a battery, and an electric lamp placed in the "center" of said wire. The question is: ...
0
votes
2answers
31 views

What possible advantage could there be in connecting several identical batteries in parallel? [duplicate]

In two-cell flash light,the batteries are usually connected in series. Why not connect them in parallel?
0
votes
2answers
34 views

How does a piece of wire know there is a voltage potential different?

Imagine water molecules inside a water pipe is moving due to difference in pressure, this pressure can be due to difference in gravitational potential or external force like somebody squeezing at one ...
0
votes
0answers
20 views

How to derive reflected waves in AC circuit?

I was reading the wikipedia page "Reflections of signals on conducting lines". In the section "Arbitrary impedance" they consider a circuit consisting of an alternating source $2V_i$ and two ...
0
votes
1answer
22 views

Is the magnetic field cancelled out in a transformer?

https://physics.stackexchange.com/a/153501/213243 In the 3rd paragraph it is said that the magnetic field from the primary windings is cancelled out by the induced current from the secondary windings....
1
vote
1answer
74 views

Does Kirchhoff's Law always hold?

There's a bit of furore from this question on Youtube involving Dr. Walter Lewin and another Youtuber. With Dr. Lewin claiming Kirchhoff's Law doesn't always hold when magnetic fields are involved, ...
1
vote
2answers
33 views

Voltage across parallel resistances

A resistor is connected to a battery of certain potential difference, it has now $V$ volt potential difference across its ends, after some time a resistor is connected in parallel with it. How does ...
0
votes
1answer
22 views

Defining potential of the ground

In electronics, it is customary to define the potential of ground (thinking the Earth as a large conductor) as zero. Is this consistent with the fact that the Earth has a net electric charge that is ...
0
votes
1answer
13 views

Why does a stepup transformer increases voltage but reduces current?

I know its a really basic question knowing the fact that you could just plug in the Voltage and Current into the proportionality formula. The thing is that I want a 'scientific/logical' explanation ...
1
vote
2answers
53 views

What is the voltage in electrical circuits?

I understand what the voltage is and I realize that the battery makes an electric field due to the accumulation of the charges in the anode and cathode this electric field causes electric potential ...
4
votes
3answers
55 views

Is there an intuitive reason the resistance that maximizes power dissipation in this simple circuit has a simple form?

Consider the following circuit: A textbook problem[2] asks to find the resistance $R$ such that the power dissipated in $R$ is maximized (assuming $R_1$ and $R_2$ are fixed). I found that $R$ should ...
0
votes
1answer
38 views

Assumptions Involved in Circuit Derivations

When deriving formulae for RC, RLC, LC circuits, etc., we typically assume that current is steady. Griffiths gave a good explanation of why this assumption is reasonable (he states essentially that ...
0
votes
2answers
41 views

AC circuit with no neutral output

I was referred here from the electrical engineering stackexchange, because my question is too theoretical. Consider the following circuit: Where $\varphi$ represents the phase of the AC power and ...
0
votes
2answers
33 views

Shot noise and single photon detection

I am looking into the noise considerations of a single photon detector, specifically an avalanche detector. I am wondering if it makes sense to think about shot noise when considering a single photon. ...
-1
votes
1answer
37 views

How a battery maintains the current in the circuit? [duplicate]

How a battery maintains the current in the citcuit? Iwant to know each and every step of this process mathematically and theoretically also.
0
votes
1answer
11 views

The value of the driving frequency at which the voltage across the capacitor becomes maximum in a series RLC ac fed circuit

The circuit diagram is as shown. As per the book voltage across the capacitor is maximum during resonance that is p=1/√(LC) But what I found out is a bit different . And it is. p=√((1/LC)-(R²/2L²)) ...
2
votes
1answer
70 views

Why is smaller hardware faster?

I have a question regarding to hardware signal. There is a rule says "smaller is faster". In the link it says that that In high-speed machines, signal propagation is a major cause of delay; ...
12
votes
8answers
3k views

Understanding voltage and power in the fluid analogy for DC circuits

I am trying to understand electric circuits (ie voltage, current, power, and resistance). For the most part, everything makes perfect sense, but for some reason I do not feel as if I understand the ...
0
votes
1answer
46 views

Magnetic field at points on the circuit

I know magnetic field lines due to a circuit always form closed loops. Therefore $\nabla \cdot \vec{B}=0$ everywhere (even at points on the circuit). However due to singularity, magnetic fields are ...
-1
votes
0answers
12 views

Parameters of transformer: open-circuit test and short-circuit test

Ok I have the following circuit and data (when the subscript is "ef" it means "rms" values): I am asked to determine the paramenters of the transformer r1 L11, L22 and LM with the given experimental ...
0
votes
1answer
37 views

Movement of electrons in a circuit

Electrons move from negative to a positive terminal, but their path seems unusual. They seem to be taking the longer path to get to the positive terminal, The electrons could have gotten closer to ...
1
vote
1answer
27 views

Why potenial drops across a resistor in an electric circuit?

Why potential drop across a resistor in circuit? I want to know what causes this drop at the atomic level.
1
vote
1answer
22 views

Why is the potential difference across a conductor is equal to the battery voltage when it is connected to it

Why is the potential differencel across the conductor is equal to the battery voltage?
0
votes
0answers
57 views

How to calculate the current generated by a thin film?

I have a thin film with known dimensions and conductivity. If I hook up wires and apply a bias, how can I calculate/estimate the current that I will get? Here is where I'm at: $$ \mathbf{J}=\sigma \...
1
vote
1answer
33 views

Confusion about calculating resistances & terminal voltage

I'm looking at an exercise where a battery is powering two parallel light bulbs. Given are the battery's EMF ($12.0 V$) and its terminal voltage in this particular circuit ($11.8 V$), as well as the ...
0
votes
1answer
29 views

Maxwell-Faraday Equation and change in magnetic flux

Is the change in flux being equal to negative emf an experimental law? The Wikipedia derivation of emf as a negative change in magnetic flux in time: https://en.wikipedia.org/wiki/Faraday%...
12
votes
5answers
1k views

What's the reason behind the current remaining the same after passing by a resistance?

I've been wondering why does this really happen, I mean by intuition if electrons are driven by EMF (ignoring wire's resistance), $n$ coulombs would pass by a point per second, until they encounter ...
1
vote
2answers
47 views

Charge accumulation at a bi-metallic junction

When we join two straight cylindrical wires of two different metals say iron and copper together such that their circular faces are in contact. If we make a constant current say I through the wires ...
3
votes
3answers
190 views

Kirchhoff's Voltage Law in a General Electromagnetic Field

Recently, Prof. Walter Lewin and YouTuber ElectroBOOM started a discussion about KVL, after Dr. Lewin claimed that KVL did not hold in the presence of an magneto-dynamic field. I would argue that Dr. ...
1
vote
4answers
66 views

What is the difference between the voltage in the electrical circuit and electrostatics?

In electrostatics it depends on the distance from the charges, should it also be in the circuit? But in practice, the voltage depends on the resistance, for example on a resistor. And the distance ...
0
votes
1answer
24 views

How do you calculate voltage drop in a neutral wire?

I've seen people saying that in practical situations, the voltage between the neutral wire and the ground is not exactly zero, is it true? And if yes, how do you find the voltage drop between these ...
0
votes
1answer
21 views

How to explain these observations on the first load, with two loads in series?

Recently I purchased the Snap Circuits Jr. kit and was working through the different projects with my daughter. We decided to connect two loads in series circuit, powered by the battery source. The ...
2
votes
3answers
42 views

Why isn't there current in R2 when capacitor is not fully charged

If we consider the switch to be closed, why would there be no current in R2. My understanding is that, as the current flows it will split into two at the junction, thus having a current charging C and ...
0
votes
1answer
35 views

Tesla coil tuning to space model

How do I model space so I can tune my tesla coil to give the most RF output at a required resonant frequency? The coil runs at 1 MHz that in aerial terms is a very short aerial so I am effectively ...
1
vote
1answer
65 views

Fourier transform of power

In the notes I am reading they use the following. Let $U$ be the voltage (depends on time) and $I$ the current in a circuit with some resistor with resistance $R$. Then the power is given by: $$P(t)=...
0
votes
1answer
53 views

How do we know that in an electric circuit, when charge leaves the battery, the same amount of charge enters the other side?

Conservation laws take the most seemingly complex of problems and boils them down to a simple abstraction, but they are huge statements to stand on. I'm just having a really hard time convincing ...
-1
votes
3answers
169 views

Does touching the Live wire makes it neutral?

If I have two 'hot' wires connected to a source and a load, and one of the wire is connected to the ground, this wire is called the 'Neutral'. But what happens if instead of using an additional wire ...
0
votes
2answers
126 views

How is Maxwell's second equation true here?

$\vec{B}=\nabla \times \vec{A}\tag1$ This is true because at every point $\nabla\cdot\vec{B}=0 \tag2$ In free space points, $\displaystyle \vec{B}=\dfrac{\mu_0}{4 \pi}\int_C \dfrac{I\ dl \times\hat{...
1
vote
0answers
11 views

Why is the maximum voltage applied to the coil different when disconnected from the battery?

In this RL circuit, the time to reach the point V=0 (after the switch was turned to (a)) was about the same as the time after switched to (b). But my teacher says, (in the experiment) peak voltage ...
0
votes
1answer
25 views

Finding the Internal Voltage and Resistance of a Battery given the behavior of the circuit it's part of

I am tasked with finding the internal resistance and voltage of a battery. I am given the following: A simple circuit consists of a real battery and a resistor in series. When the resistor's ...