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

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1answer
54 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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0answers
20 views

Flow of alternating current in an ac circuit [duplicate]

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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0answers
16 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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1answer
50 views

In a circuit, if voltage is established at both terminals, then how can components use up this voltage? [duplicate]

Suppose we use a 9V battery. Then the voltage between these two terminals is 9V. In other words, it would take 9 J of energy to move +1C of charge from the (+) to the (-) terminal by the electric ...
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27 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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1answer
135 views

Why is the potential difference across these two capacitors both 9V?

So above are two difference circuits, each with a 9V battery and a capacitor of the same capacitance. $C_1=C_2$ Why is the potential difference across both capacitors 9V? Shouldn't it be less than ...
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1answer
37 views

Electrical network of current sources - What happens if one source is defect?

Suppose you have connected in a parallel circuit a pair of, say for the sake of concretness 5 sources of 300 mA and 0,5 V each, which are themselves connected together in series. Hence, in total one ...
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2answers
324 views

Is there a simple proof that Kirchhoff's circuit laws always provide an exactly complete set of equations?

Suppose I have a complicated electric circuit which is composed exclusively of resistors and voltage and current sources, wired up together in a complicated way. The standard way to solve the circuit ...
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2answers
415 views

Is there inductance to a DC circuit?

When a DC circuit is carrying current, large amounts or small, is there induced-emf due to the inductance? Or is it only applied to AC circuits?
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32 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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1answer
47 views

What happens if connect 2 points with different potential?

I have a very basic question on charge distribution in electric circuits. Let's say we have 2 independent circuits. If we connect a point with higher potential in one circuit to a point with a lower ...
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2answers
304 views

Is there a formal proof for the superposition theorem?

I was just wondering whether there is a formal prove for the superposition theorem in electric circuits? I tried searching it online but couldn't find anything sufficient. Most of the sources assume ...
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1answer
82 views

Is a CRT / Electron gun in need to be in a closed loop?

I'm trying to understand electricity and there for electrons. And so far i believe i am grasping it. But there are a few parts i have a hard time understanding. For example in as i understand it, in ...
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21 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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3answers
105 views

Resistance of capacitors

Please I would like to know how the resistance of the plates of a capacitors work? Is it the same as a resistor? If yes, is there electric field inside the plates like inside a resistor?
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2answers
2k views

General integral to find resistance

My question is: is there a simple and truly general equation for the resistance between two electrical equipotential surfaces?. Obviously, if so, what is it, and if not, why? It would be very ...
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1answer
74 views

Diffusion current and resistance of a diode

In a diode, there is a resistance in the p and n region, and electric field is required to move the charges in forward bias conditions. My question is: when there is diffusion current is the electric ...
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1answer
87 views

Calculate the resistance in serial and parallel circuits

I have a serial and a parallel circuit. In both of the circuits I am using two resistors.These two resistors have the same resistance $a$. In both the circuits I have tried reading the amount of ...
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4answers
123 views

Current in purely LR DC circuit at t=0

I was told by my professor that the current in a purely LR Circuit with at initial state (JUST after closing the switch) is zero. Can you please help me understand why it that so?
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2answers
40 views

Why can't I get a output lower than 0V in this circuit?

In the image above green is my input (node left side capacitor) and blue is my output (node right side of the capacitor). I would expect that the blue sinusoidal looking signal would follow the ...
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3answers
8k views

Reducing Eddy current losses

Eddy currents are setup in any metallic block which is in the vicinity of changing magnetic fluxes. These primarily cause heat losses, and in certain cases causes damping of the relative motion ...
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1answer
61 views

How should I interpret the math in showing that the potential difference and the emf in an ideal battery are the same?

I was reading Griffiths' Introduction to Electrodyamics where he says that in order to have the same current through out a circuit there are two force per unit charges acting on the circuit, $f=f_s+E$ ...
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1answer
69 views

Help me understand static electricity

This is what I understand about electricity: (The following information is paraphrased from the book CODE by Charles Petzold.) Atoms are made up of protons, electrons and neutrons. Protons and ...
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1answer
332 views

How does a magnetic field produce an electromotive force?

As I keep reading through texts and online, I keep getting conflicting views when in magnetic fields and electromotive forces are involved. From what I can see, the emf is the work done per unit ...
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49 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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6answers
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What is Electromotive force (EMF)? How is it related to potential difference?

What is Electromotive force (EMF)? How is it related to potential difference? Is it the creation of potential difference in any conductor??Is it a process?Why is it called force? Does writing emf ...
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1answer
144 views

Loading a capacitor in an RC circuit

I have an RC circuit to which I am going to apply voltages of 5V every 100ns. So every 100ns, the capacitor will change its "state" from charging up to uncharging. I have been trying to find the a ...
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544 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

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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56 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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2answers
2k views

Can we pass electricity through air?

Electricity: I was wondering, whether we can pass electricity through air over a distance of 100 meters or so as electricity means the flow of electrons and we have seen the discharge or movement of ...
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4answers
167 views

Current and voltage word problem [closed]

If a conductor with a current of 200mA passing through it converts 40 J of electrical energy into heat in 30 seconds, what is the potential drop across the current ? The answer is 6KV, but I don't ...
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2answers
412 views

Olympiad physics 1996 problem [closed]

I don't understand the official solution of the first problem of the 1996 International Physics Olympiad. They give this circuit: Each black box is a resistor of resistance $1\Omega$. They then ...
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1answer
51 views

Why isn't this a valid derivation of the formula for capacitors in series?

I had to derive the formula for capacitors (I decided to use m capacitors in my derivation) in series, and this is what I did. The formula for a capacitor is $$Q=CV,$$ which is the same as saying ...
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66 views

Thermometric Properties

A thermocouple thermometer with 10 ohms of resistance is calibrated with its hot junction and cold junction immersed in steam and melting ice respectively. An EMF of 5.6mv is measured. This ...
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20 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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1answer
221 views

Name of battery voltage when load connected/disconnected

If I had a 3V battery, and when no load connected it reads 3.2V, and with a load 2.8V (just a hypothetical example), what is the name for these two terms, with a load or no load? I know the voltage ...
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1answer
91 views

Scattering Matrix of a Given Circuit - Microwave

This might be an easy question but I couldn't find it in our course book[Microwave Engineering, Pozar, 4th ed] or on internet. I have a homework and one of the questions asks me to find the S-Matrix ...
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2answers
46 views

What dynamical system could this $\dot y = \alpha(y-\lambda), y\geq \lambda$ equation describe?

Just out of curiosity, can anyone identify electrical, mechanical, chemical, etc process that is governed by a differential equation of the form $$\dot y = \alpha(y-\lambda), y\geq \lambda$$ where ...
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1answer
72 views

Load resistance adding with minimized power and voltage constraint [closed]

Consider the simple circuit below: Suppose $V$ and $R$ have set voltage and resistance values respectively, and you are to choose the resistance values for $R_1$ and $R_2$. However, you must choose ...
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1answer
30 views

Showing $\frac{\delta V_{out}}{V_{out}}=\frac{\delta R_2}{R_2} \frac{R_1}{R_1+R_2}$ [closed]

Consider a voltage divider with $V_{out}=V_{in} \frac{R_2}{R_1+R_2}$. Show that for a small change in $R_2$, the voltage divider equation is: $\frac{\delta V_{out}}{V_{out}}=\frac{\delta R_2}{R_2} ...
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3answers
413 views

Defining Reference Directions for Voltage and Power (sign convention)

My professor decided to use the above reference directions when calculating power in circuits. He says that when power > 0, power is consumed. When p < 0, power is generated. This definition is ...
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48 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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1answer
114 views

Electrical Analog of a Chain of Springs

I'm trying to wrap my head around the Force $\rightarrow$ Voltage analogy between mechanical and electrical systems. I have a mechanical system where masses are connected by springs in series, and ...
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3answers
625 views

The role of resistor in e.g. an AND gate

What is the role of the resistor in e.g. an AND gate like this one? : One often sees lots of resistors in electric circuits, but I haven't really understood their role.
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3answers
6k views

Why does the current stay the same in a circuit?

I was informed that in a circuit, the current will stay the same, and this is why the lightbulbs will light up (because in order for the current to stay the same, the drift speed of the electrons need ...
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2answers
2k views

Why is the voltage drop across an ideal wire zero?

I'm having trouble conceptualizing why the voltage drop between two points of an ideal wire (i.e. no resistance) is $0~V$. Using Ohm's Law, the equation is such: $$ V = IR \\ V = I(0~\Omega) \\ V = ...
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1answer
81 views

Dependence of the Capacitance on the Material and Geometry of the Plates

I have two questions concerning capacitors: 1) We know that the capacitance of a capacitor also depend on the dielectric material inside as $C=$ $\dfrac{K \epsilon_0 A}{d}$ But what if the ...
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4answers
121 views

Measuring electric conductivity

My daughter is doing a science experiment on which metal (e.g., copper, silver, aluminum, iron) has maximum electric conductivity. We are assuming we can accomplish this by using different metal, 3 to ...
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3answers
372 views

Why is emf equal to PD when circuit is “open”?

I understand that the set up of a battery consists of very good, but not ideal conductor, and therefore, some internal resistance exists. Also, I get that emf is the PD that would exist if the ...