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

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128 views

Are magnetic hysteresis losses relevant to alternating currents flowing in a wire?

Say we have an AC in a magnetically lossy material, like iron. Because of iron's relatively high permeability, skin effect will be more pronounced than it is in say, copper, so this iron wire isn't so ...
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1answer
86 views

Why does current density have a direction and not current?

As I understand it the definitions are as follows: Current is a scalar $I$ with units of $\mathrm{[J/s]}$. It is defined as $I=\frac{\mathrm{d}Q}{\mathrm{d}t}$. Current density is a vector $\vec{J}$ ...
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74 views

Avoid dependent equations when applying Kirchoff's Laws

I tutor college students in Physics. In particular, we are currently working on solving circuits using Kirchoff's Laws. In a recent problem, I ended up with a system of linearly dependent equations ...
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1answer
21 views

Flux linkage of 2 coils in series

I have a question from magnetic circuits. I am an engineering student, therefore I will neglect some minor errors. There is a simple magnetic circuit with 2 coils ($C_1$ & $C_2$), with $N_1$ ...
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121 views

RLC circuit, turning off the voltage source

An RLC circuit (pictured above) is governed by two equations: $$ -iR=-L \frac{dj}{dt} = \frac{q}{C}+V(t) $$ $$\frac{dq}{dt}=i+j$$ q satisfies the equation: ...
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65 views

Why are ammeters used in series and voltmeters in parallel?

As I'm reading a course on electricity, this one says that an ammeter should be branched inline and not on a bridge. Can someone explain to me physically why we branch a amperemeter inline and a ...
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23 views

Why is the current measured through a thin film increasing with time? (experimental question)

I'm doing an experiment: I'm thermally evaporating a metal in a vacuum onto a quartz (very insulating) substrate, between two gold contacts that I use to measure the current through the (growing) ...
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118 views

Concepts in Gabriel Kron's later papers

Gabriel Kron was an important research electrical engineer known for applying differential geometry and algebraic topology to the study of electrical system. Towards the end of his career he published ...
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64 views

How do the different types of energy apply to voltage in a circuit

I was just wondering what happens in a circuit in terms of different types of energy transformations. If you apply a voltage to a circuit then electrons start moving (very slowly). Since the electrons ...
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89 views

The origin of contact noise?

I was trying to measure the noise of a device with metal probes. I was not sure whether I should trust the results because I was told contact noise might contribute to some degree. I am a little ...
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0answers
18 views

Equivalency of Q Factor Definitions

The Q factor is defined (seemingly) as $$Q=2\pi\frac{\mathrm{energy \, \, stored}}{\mathrm{energy \, \,dissipated \, \, per \, \, cycle}}$$ however on Wikipedia is says that the Q factor can be ...
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98 views

Energy of RLC circuit

If you are given a general differential equation for an RLC circuit, for example, $$L\left(\frac{d^2 Q}{dt^2}\right) + R\left(\frac{dQ}{dt}\right) + \frac QC = V\cos(\omega t),$$ which is a driven ...
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38 views

To find the center of charge in current waveform

I have a circuit for which output current waveform has both positive and negative points. Now I want to get a center of the charge for this waveform (means where my net charge is concentrated ?). Is ...
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48 views

Questions (intuitive) about circuits and the flow of electrons

Why don't electrons accelerate in a circuit? If there is a potential difference and the electron moves in the circuit a force is exerted on it. Why does that force produce no acceleration, keeping the ...
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88 views

Voltage in a lossless transmission line

I have a question where I'm deriving expressions for different variables within a lossless transmission line. Here's the question as posed: Consider a lossless transmission line of characteristic ...
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116 views

Different phase in capacitively coupled RLC circuits

I was trying to work with some data for a lab report I'm writing about capacitively coupled RLC circuits. The setup is pretty simple and looks like that: Where $C^{'}$ is the coupling capacitance. ...
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123 views

How is derived the relation between capacitances when a $Y-\Delta$ transformation is applied in a capacitors network?

A $Y-\Delta$ transformation can be applied to circuits in order to make an equivalent circuit (but simpler to put in terms of series/parallel devices). Wikipedia and other books show how to deduce the ...
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74 views

How power affects heating of a coil

So I am doing a little research on my own about electronic cigarettes. Most Ecig users value high power at a standard current. This means they buy very expensive, high voltage batteries and put high ...
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95 views

How to size an electromagnet

How can I size an electromagnet? For example if I would to attract a mass of $x$ kg what are the calculations that I must do to size the ferromagnetic core and of course the solenoid? And thus, how ...
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173 views

Braess's Paradox in Electrical Circuits

According to this and other similar papers, http://www.nature.com/nature/journal/v352/n6337/abs/352699a0.html, adding a current-carrying path can increase the voltage drop across a circuit. What is ...
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294 views

Algorithmic approach for applying Kirchhoff's Rules to circuit analysis

Working with Kirchhoff's rules, I am attempting to device an algorithmic approach to finding the unknowns of the problems, I am of a Computer Science background and I am finding it difficult to ...
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16 views

Flow of alternating current in an ac circuit

I know that it the frequency of an alternating current is 50Hz.It changes its polarity 50 times. So in a circuit does the polarity gets changed these many times. It seems that it is well applicable in ...
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13 views

Current flow in a polarized capcitor

What is a polarized capacitor? I have learned that in a polarized capacitor, the negative lead must be connected to the negative terminal of the battery and so the positive. But my doubt is that if ...
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16 views

Resistance of depletion region

The ideal diode equation is : I=Io[exp(qv/kT)-1]. My question is when we want to represent this ideal diode, it will be represented by a resistance of depletion region right? but is this resistance ...
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22 views

Potential difference on a curcuit

Above is a simple circuit. It has a voltage of 9V between the two terminals. I have drawn red lines which look like vectors, indicating how the current will flow. From the above diagram, I have a ...
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15 views

Problem with the sign of the Thevenin resistance in a circuit

I have the following issue: when I want to find $R_{Th}$ for a circuit with dependent sources, I excite the circuit with a voltage Vo, and then proceed to find the resulting current $I_0$. Finally, ...
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20 views

How does current flow in the circuit during negative cycle of input?

So,as far as I know the input signal just controls the current from +Vcc as per this analogy But in the first picture during the negative half cycle of the input waveform the output wave form is ...
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83 views

Difference between rheostat and potentiometer & How connections are made to a simple rheostat?

I am confused about connecting wires to a rheostat. Can you please name and explain the parts of rheostat? Also how do we know which end of rheostat is to be used in circuits? In the last picture ...
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27 views

Electron flow through insulators connected to conductors

I imagine a simple circuit consisting of a power supply and conductor connected to an insulator (heavy resistor in series with wires). In a closed circuit, I understand that the battery's E field ...
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19 views

Is this the creation of an electrical circuit

If I place a aa battery on the negative side and a aa battery on the positive side on to a stainless steel surface and then place a quarter on the other side have I completed an electric circuit? Is ...
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29 views

Probe/Sensor-design for pulsed electromagnetic field

So I have a wire/coil, acting as a sender, which has a pulsed signal as described below. I would like to build a sensor/probe that can detect the electric field at a distance, where the primary goal ...
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33 views

capacitors - Square circuit of two capacitors charging in a changing magnetic field

I've been studying capacitors and DC circuits, and I received this question as part of my homework: The above circuit is a square circuit with side a. E and F are the midpoints of AB and CD ...
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73 views

Thevenin's equivalent of Wheatstone bridge

I tried to calculate the Vos and Isc and both of them are zero..so the Thevenin's resistance is 0/0=undefined. How do I calculate the resistance when Vos/Isc fails,such like the Wheatstone ...
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31 views

Why is voltage input different from voltage output in a circuit?

This is more specifically, when performing the meter bridge experiment. The meter bridge experiment is an experiment in which using the meter bridge, a jockey, voltmeter, battery eliminator, you keep ...
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18 views

Is it possible that intermittent current is being passed in a circuit with loose connections at less than maximum capacity?

In a circuit, the wires may not have been connected properly and a connection is loose somewhere. Is it possible that intermittent current is being passed in a circuit at less than maximum capacity?
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44 views

The mathematical physics of saltatory neuron action potential transmission

Some time ago, I tried to understand saltatory electrical potential transmission on a myelinated axon but have not found a clear mathematical model of this mechanism. I understand the cable theory, ...
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37 views

Making elementary guess regarding current in AC circuits

I was just studying the comparisons, between A.C, and D.C, and the effects they can produce in electrical circuits (viz, Joule-heating, Peltier-effect and Seebeck-effect in thermocouples, ...
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26 views

Origin of Overpotential in Electrochemical Cell

I'm well aware of the significance of overpotential and how it is defined to be the difference between the thermodynamically determined equilibrium potential and the experimental potential required to ...
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25 views

Replacing diode in circuit analysis?

While analyzing circuits containing diodes in reverse bias I replace it with a pure insulator for simplifying things. Similarly can I replace a forward biased diode with a conductor and a varying ...
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98 views

How to apply Faraday's law to LC circuit?

I am having problem on using Faraday's law correctly. When I try to apply Faraday's law to the LC circuit: Assume the top plate of capacitor is positively charged and bottom is negative. So no ...
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116 views

Power wasted and power delivered?

If a power source is supplying a current I and a voltage V, that travels to its destination through resistors of restance R is the power delivered at the destination = $VI - RI^2$, where $(Pi=) VI$ is ...
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62 views

What is the best way to measure bioimpedance using AC bridges

What is the best way to measure bioimpedance using AC bridges? and capacitances?
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139 views

Thermal noise from capacitor; circuit analysis

I'm trying to model the thermal noise from a capacitor. The capacitor is connected directly into an amplifier with resistance $R_{A}$ and capacitance $C_{A}$. A noisy capacitor is modelled as a ...
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57 views

What is a non-linear capacitor?

I'm new here. I have a (maybe dumb) question: What are non-linear capacitors? I'm given a circuit including a capacitor and the question says The given capacitor is non-linear with the ...
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62 views

Does back emf occur in transformers?

Does back emf occur in transformers and if so does it reduce the efficiency of the transformer and can it be reduced?
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58 views

Kirchoff Loop and current

The pic of the circuit/problem: I got the problem right, but i want to make sure my reasoning is correct for the current left of the 2.1 V battery. Its the same current as $I_1$ because the ...
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50 views

Balanced three phase circuit Y-Y with neutral

Here is my equivalent balanced three phase circuit Y-Y with neutral: Rla + jXla is my line impedance by phase. L1 and L2 are my loads. The exercise is saying that L1 absorbs 180 W and 240 VAr, L2 ...
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61 views

Blocking electro-magnetic waves between two near field antennas

Its been a while since I studied physics, so pardon my ignorance. I have two near field antennas. The range of the antennas is about 2-3 cm. I am looking for a way where I can block and unblock the ...
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113 views

About electric current analogy

my teacher gave me this analogy to the electric current , the wire is like a pearl necklace where the pearls can move, the current or the movement of electrons is like putting your fingers between 2 ...
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143 views

Transfer functions of active filters

I've been looking for some straightforward method or trick to obtain the transfer functions of active filters (like the Sallen-Key filter, the butterworth or Cauer topology etc...) since KCL or KVL ...