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For a given amount of resistance (combined resistance of all the circuits in your computer, or home, or city), the amount of current which flows is proportional to the voltage. (I=V/R) When lightning strikes a line, it induces a voltage spike. Traditional circuit breakers are current-sensing devices (whether solid state or electromechanical). So, a ...


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You're quite correct that there will be some current flowing, so there must be a voltage drop due to the internal resistance of the battery. The EMF measured by any voltmeter will always be less than the true EMF. If the internal resistance of the battery is $R_b$ and the resistance of your voltmeter is $R_m$ then the voltage you measure will be: $$ V = ...


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There are two basic systematic approaches for analyzing a circuit like this: nodal analysis, which uses Kirchhoff's current law (KCL), and mesh analysis, which uses Kirchhoff's voltage law (KVL). The two methods would work about equally well for this particular circuit, in that both methods would require solving a system of three equations in three ...


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The admittance looking into the network "$Y_{net}$" can be expresed as: $$Y_{net} = \dfrac{1}{R + \dfrac{1}{Y_{net} + Y_{diode}}} $$ Rearranging as a quadratic and solving: $$Y_{net}^2R + Y_{net}Y_{diode} - Y_{diode} = 0$$ $$Y_{net} = \dfrac{\sqrt{Y_{diode}}\sqrt{4R +Y_{diode}}}{2R}$$ Where $$Y_{diode} = \frac{nV_t}{I_s}e^{-\frac{V_f - I_fR}{V_t}}$$ ...


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gee whizz, its like Maxwell and Faraday never existed! Remember, a current carrying wire gives rise to a concentric magnetic field. This will be accompanied with a radial Electric field.


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Yes, your circuit on the right models a chain of springs intersperced with masses. Think about it. It should be obvious from frequency analisys alone that the left circuit can't be right. Springs with masses are going to low pass filter any force or motion input. The left circuit clearly high pass filters, not low pass.


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It's not a fundamental feature of electrical potential, but: If you have a polycrystalline metal and you cut and polish a smooth surface, the differently-oriented regions will present a different lattice plane to the outside. Crystals cut along different planes may have slightly different work functions, and so the electric potential very close to such a ...


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This is because what changes in each resistor is the current passing through and not the voltage difference. One the other hand when resistors are in series they have the same current passing through, but different voltage through each one's nodes. In essence when resistors are in parallel do not share same current path (i.e wire) but share same voltage. On ...


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Kirchoff's laws tell us that the potential drop across any closed loop in a circuit must be equal to the voltage sources in the loop, from which we conclude that the voltage drop across resistors in parallel must be equal. Ohm's law states: $$V=IR$$ From which we conclude that, since $V$ is fixed, if the different resistors have different $R$'s, then the ...


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For static charges, the relationship is V (voltage) = Q (charge) / C (capacitance). Capacitance is a function of the shape, size and distance between objects, which are all continuous values. (Well, I suppose you could argue that shape and size are quantized to the atomic spacing of the object's material, but you can't say the same thing for distance.) So ...


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Voltage is a continuous function. If you are a certain distance from a (point) charge $q$, the potential is $$V=\frac{q}{4\pi\epsilon_0 r}$$ By adjusting the value of $r$ to anything you want (not quantized), you can get any potential you want. And so yes, when you do any analog-to-digital conversion, you will "destroy" a certain amount of information. ...


5

Voltage doesn't come directly from the charge of the electron. It's the energy per charge. The charge carriers may be discrete, but the energy is not. We can easily generate a potential by moving a wire through a magnetic field. The potential is proportional to the speed of the wire, which is a continuous value. $$V = vBL\sin{\theta}$$


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As radio amateurs we've all learned the various relationships of power, voltage, current and resistance as expressed in Ohm's Law Ohm's law is: $$ E = IR \tag{1} $$ This doesn't directly say anything about power. There is the related Joule's first law, which relates to electrical power converted to heat in resistive materials: $$ P = I^2 R \tag{2} $$ ...


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As Kevin Reid aptly explains, the circuit you have drawn is not realizable. But, let's take the closest physical thing you could build, assuming: your voltage source can supply enough energy that we don't hit its limits like all physical things, this apparatus has non-zero size Then, the circuit you actually built is this: simulate this circuit ...


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In problems of this type, it's required to determine the initial conditions. Often you might have to work them out from analyzing a modified circuit (for example, with a switch in a different position). But it's also possible the initial conditions are simply given as part of the problem statement, and that seems to be what was done here. If your professor ...


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Intuitively, inductors create back EMFs that "resist" changes in current. Anytime there is an inductor in a circuit, it will resist such changes. Mathematically, inductors force the current in a circuit to be continuous. Let's consider an LR circuit where the inductor and resistor are both in series. Regardless of the initial voltages or current, we can ...


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The voltage drop across an inductor is proportional to the change in current, or V = L*dI/dt. When the switch is closed, the circuit is completed and a current starts to increase dramatically. This then causes a time increasing flux of magnetic field in the inductor. According to Lenz's Law, an opposite current will be induced in the inductor to oppose the ...


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… an ideal power source capable of providing infinite current with no drop in the voltage it supplies. … Let's ignore the effects of current density on superconductors for now. … In these phrases is the explanation for the contradictory possibilities you have computed: you have supposed an impossible circuit. As a mathematical model, the behavior of ...


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“[A]n equal and opposite field” is an oxymoron and gibberish. Henceforth I’ll assume that we have a chemical voltage source there. The Coulomb’s law is applicable in the case of a charged body, a body that has a constant electric charge. A chemical voltage source is a completely different situation: there is no pre-defined distribution of charges (as they ...


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The measure $ R $ of resistance is an invented one. It was deduced long ago by experiment that many materials had a constant ratio $ \frac {V}{I}$ between the voltage applied and the current flowing. Thus the quantity 'resistance' was defined to be precisely this ratio. Later, when inductive and capacitive effects were observed, 'reactance' $ Z $ was defined ...


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Whether EMF is a kind of voltage or not depends on terminological conventions. EMF certainly has the same dimension as the voltage (a.k.a. electric tension) has. They are customarily added or subtracted in formulae related to voltage sources such as $U = {\mathcal E} - I\cdot R_{\rm int}$. But these ${\mathcal E}$ and $U$ are no more the same quantity as ...


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No real transformer is lossless, the output power is always smaller than the input power. One can, however, build transformers that have extremely precise voltage and current ratios (but none of those are transferring any power). Such transformers are being used in calibration and measurement applications.


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The voltage across the battery when there is zero current (no load connected) is called the open circuit voltage. The emf of the battery is equal in magnitude to the open circuit voltage. I'm not certain that there is a standard term for the battery terminal voltage when a load is connected since, in general, this voltage varies with the load. One might ...


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$P = IV$ applies to all circuit branches. $P = I^2R$ or $P = V^2/R$ are restatements of the general rule that apply when we are considering power delivered to an ideal resistor that behaves according to Ohm's law $V = IR.$ I have seen in some circuit $V^2/R$ is not equal to $I^2R$ (like when there is capacitor or inductor). Why is that? Those ...


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There is an ambiguity. Although I did not understand your analysis of the problem completely, charge carriers certainly can run against the (averaged) electric force due to difference in available bands and other particle statistics effects. The gauge freedom is irrelevant. There are two cases for the “ubiquity”. First, these non-Maxwellian deviations ...


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The distinction between emf and potential difference is often glossed over and often misunderstood so this is an appropriate and interesting question. Since both emf and potential difference are measured in volts, it is quite easy to use the terms interchangeably and, in many cases, there's no harm done but that fact is that emf and potential difference are ...


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You should not think of electrons throughout the circuit as one part having more electrons than the other. You should instead think of the electrons within the conductors in terms of their energy. For example when you connect have a simple circuit with a battery, a set of wires, and a load. When you close the circuit, the electrons at the negative side of ...


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EMP or PD is the "pressure" of the electrons. You can have a very high EMF with no flow at all. "Flow" is actually measured by the amount of charge (Coulombs) per second and is measured in Amperes.


1

What is the flaw in my thinking? The voltage across the capacitor in the series RC circuit given, assuming zero initial capacitor voltage, is given by $$v(t) = E\left(1 - e^{-\frac{t}{RC}} \right), t \ge 0$$ Note that $v(t) \rightarrow E$ as $t \rightarrow \infty$. The energy stored in the capacitor, as a function of time, is $$U(t) = ...


1

Once the capacitor has fully charged the current in the circuit will be zero, so the voltage drop across the resistor is zero and hence the voltage across the capacitor is equal to the cell voltage. Having said this, the current falls exponentially with time so in principle the current takes an infinite time to fall to zero, and the voltage across the ...


1

Ohm's law won't get you very far when dealing with RC circuits (R=resistor, C=capacitors). The general way to deal with such circuits, as described in the WP page on RC circuits, is to use Kirchhoff's circuit laws to write down a differential equation. Solving the differential equation will give you $I(t)$. The basic idea to applying the appropriate ...


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Radio wave receivers are designed to resonate at a particular frequency. If you look at the response of a resonant device as a function of frequency you get something like (this image is from the Wikipedia article): This is a rather busy plot, but the point to take away is that the response of the resonant system is greatest when the frequency matches the ...


3

why doesn't the receiver of this device happen to catch another wave of the same frequency instead of the one that was intended? It does catch other waves at the same frequency. This is called noise. Communications are engineered so that the signal is significantly stronger than the potential noise such that it can still be reliably demodulated. More ...


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In the limit of long times, the currents are steady, so the magnetic fields they create are steady so there is no induced EMF. This situation is usually tagged "steady state". That said, there will be a period of time when you have just switched a circuit on or off during which things have not settled down and then there will in general be effects not seen ...


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To add to Floris's reply, just to elaborate in a very basic manner in what way the flux linkage (analogous of displacement x in Force Current analogy) and magnetic flux differ. Consider the scenario where a magnetic field is present, and we have an open circuit that has been closed using a metalic rod. As the picture shows: We know that the induced EMF ...


2

I think there is something wrong with your mapping. Looking at http://lpsa.swarthmore.edu/Analogs/ElectricalMechanicalAnalogs.html , I see the following table: This is inconsistent with the mapping you are showing. I can understand this table - I can't understand yours. I think an error crept in - which would reasonably explain your confusion. Looking ...



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