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

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3answers
104 views

Theoretical uncertainty of a circuit's total resistance when made entirely of resistors

My question in short(ish) is: Will the fractional uncertainty of a circuit made entirely of resistors with equal fractional uncertainties be the same as the fractional uncertainty of those resistors. ...
3
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4answers
66 views

How does an inductor store magnetic energy?

I am trying to figure out what the potential energy of an inductor with a current really means. In a capacitor, the energy stored works like this: if you let the plates attract each other, before ...
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2answers
27 views
0
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1answer
84 views

Work done in a capacitor with a conductor between its plates [on hold]

I have been agonizing over this problem, and have tried for more than two hours two find it with Kirchhoff equations, but I end up with 0=0 or some algebraic monstrosity. I have the following ...
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2answers
41 views

Doubt on resistor circuit [on hold]

How are we able to flip the triangular resistor to the opposite breaking its connection with the lower 2r resistor?
0
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1answer
93 views

Back EMF & Current, how can we make the current $I$ stable?

Lets assume we have a wire that has $10V$ across and $1$ $Amp$ flowing, now if this conductor is introduced to a changing magnetic field, $-EMF$ is induced, can we control our voltage to increase it ...
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0answers
18 views

How to calibrate an ammeter and voltmeter? [migrated]

How can I calibrate an ammeter and a voltmeter. I just want to know about it. Because it might be helpful and I think it is a vital thing to know. So how can I do this?
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1answer
13 views

The working of rheostat/ potentiometer [on hold]

I can't grasp the concept of how a rheostat divides potential and acts as a variable resistance in a circuit.I have tried asking my teachers and fellows but their explanation hasn't been satisfactory. ...
0
votes
1answer
111 views

Measured voltage on coil

I have a simple circuit of coil with inductance L $$u_c(t)= -L\frac{di}{dt}$$ and AC source with output voltage $u_s$ What is actually measured by the voltmeter ($u_c$, $u_s$ or $u_s - u_c$)? If ...
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5answers
764 views

What causes contact resistance?

When two components are combined in an electric circuit, there is apart from their own resistances a contact resistance at their junction. This causes a sudden voltage drop of ...
3
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1answer
157 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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2answers
253 views

Having trouble understanding the concept of current and Ohms law

Circuit in series: $10\,\text{V}$ power supply, 2 resistors connected. Each resistor is $10\,\Omega$, total of $20\,\Omega$ resistance. If I put an ammeter at the end of the circuit, will the current ...
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2answers
46 views

Why is voltage essential in circuits?

I understand what voltage is, but why is it necessary for an electric circuit to function? Why can't current flow without a voltage?
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0answers
29 views

I tried to solve circuit analysis problem but it failed [closed]

I tried to solve circuit analysis problem in Hayt's Circuit Analysis 7th. But my answer is wrong and I don't know why I failed to solve this. Here's the question. I have to find what the value of v3 ...
2
votes
2answers
13k views

Current in series resistors and voltage drop in parallel resistors

when we have resistors in series, the current through all the resistors is same and the voltage drop (or simply voltage) at each resistor is different. Question 1: it is fine that voltage drop ...
3
votes
1answer
164 views

RLC circuit, turning off the voltage source

An RLC circuit (pictured above) is governed by two equations: \begin{align} -iR &= -L \frac{dj}{dt} = \frac{q}{C}+V(t) \\ \frac{dq}{dt} &= i+j \, . \end{align} $q$ satisfies the equation ...
0
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0answers
24 views

What is the capacity of this circuit? [duplicate]

I simply can't figure out what the capacity of this circuit is. I can do the math myself, I just need a hint how to create an equivalent circuit where it is obvious what is parallel and what is in ...
2
votes
1answer
62 views

Why do high voltage transmission line workers need a Faraday cage suit?

In this video the high voltage transmission line workers are wearing a Faraday cage suit. Why is this needed? Without the Faraday cage, the resistance of the human would be very high compared to the ...
1
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1answer
35 views

Highly inductive circuits question in general

I've been reading about self-inductance in circuits in M. Purcell's Electricity and Magnetism and came across an interesting fact: "What happens if we open the switch after the current $I0$ has been ...
1
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1answer
63 views

Electric Motors: why do they draw more current when stalled, and less when moving? [duplicate]

I'm familiar with how an electric motor works, and also familiar with what stall current and free current refers to in an electric motor. I'm also somehow familiar with the notions of energy being ...
0
votes
1answer
26 views

Does the power of the resistor change when the battery is changed?

Wanted to know whether the changing of a battery (potential difference)affects the change of power consumption of a resistor of a bulb. please tell me how the change will occur?
0
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0answers
48 views

Resistance of a metal sphere

How would you go about calculating the electrical resistance of a sphere when you only know it's radius and conductivity? I know with cables you can use $$ R = L/(g \cdot S),$$ but I don't know how ...
5
votes
1answer
66 views

Does the skin effect, eddy current / hysteresis losses contribute to Johnson noise in an inductor?

Based on my very basic understanding of the Johnson noise, it's not just a DC phenomena, but should change with frequency in a system, where there is a frequency dependent, real component to the ...
0
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1answer
191 views

Finding the voltage of the circuit?

Capacitor 3 in Figure (a) is a variable capacitor (its capacitance C3 can be varied). Figure (b) gives the electric potential V1 across capacitor 1 versus C3. The horizontal scale is set by C3s = 20 ...
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1answer
31 views

Are LC circuits preferred as series or parallel? Why? [closed]

Are LC circuits preferred as series or parallel? I recently studied about LC circuits in parallel and asked my tutor about whether the inductor and capacitor could be connected in series. He said it ...
55
votes
2answers
36k views

On this infinite grid of resistors, what's the equivalent resistance?

I searched and couldn't find it on the site, so here it is (quoted to the letter): On this infinite grid of ideal one-ohm resistors, what's the equivalent resistance between the two marked nodes? ...
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3answers
3k views

Proof of Thevenin and Norton theorem

How can I prove Thevenin's and Norton's theorem? Thévenin's theorem can be used to convert any circuit's sources and impedances to a Thévenin equivalent.
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0answers
22 views

Kirchoff's circuit law matrix representation

A couple of recent Kirchoff's law questions with wacky geometries got me thinking. "Solving" any circuit that consists only of resistors and e.m.f. sources can be reduced to solving a linear system of ...
0
votes
1answer
25 views

Calculating resistance [duplicate]

I am really confused please help me! I want to find the resistance between a and b! But i am not able to understand which resistances are in series or which are in parallel! What i think- e and a ...
0
votes
2answers
4k views

Conversion of Moving coil galvanometer to ammeter

A galvanometer can be converted into an ammeter by connecting a low resistance (called shunt resistance) in parallel to the galvanometer. Firstly, why do we need to connect the resistance? If a ...
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2answers
39 views

potential difference across a bulb

I am doing some self studying over the summer for fun and I'm working from a book that does not provide answers. I came across the following question, and I will present my solution. I was hoping ...
0
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0answers
18 views

Total current - differential equation [duplicate]

Consider the circuit below consisting out of a capacitor C and two identical resistors R. For $t<0$ the switch is open and the capacitor is uncharged. At $t=0$ switch is shut and the circuit is ...
0
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0answers
29 views

LC-circuit with AC-supply - Current flowing through the coil

A parallel LC-circuit is connected to an AC-supply as in the figure below. $I_{tot}(t)=I_0sin(\omega t+\phi)$, $\phi$ is the phase angle between $V_{tot}(t)$ and $I_{tot}(t)$ a) ...
0
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3answers
31 views

Why do inductors maintain the exact same current?

As we know, a capacitor will maintain the same voltage across its poles even if it is disconnected from a battery source. For example, in this problem: http://www.unm.edu/~toolson/rc_circuit.gif ...
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1answer
45 views

Circuit with capacitor and two resistors - total current - charge - differential equation [closed]

Consider the circuit below consisting out of a capacitor C and two identical resistors R. For $t<0$ the switch is open and the capacitor is uncharged. At $t=0$ switch is shut and the circuit is ...
1
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1answer
26 views

Loss in energy while charging a capacitor

Suppose a capacitor having capacitance $C$ is being charged using a cell of emf $E$. By the time the capacitor is fully charged, the cell has supplied $QV$ energy while the potential energy of the ...
4
votes
2answers
359 views

Energy conservation when capacitor charges in a zero resistance circuit

We know that when a capacitor charges from a source $E$, it stores energy of $E=\frac{1}{2}QV $. This is derived without taking into consideration any resistances present in the circuit. We also ...
0
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0answers
32 views

Maximum current in LC Circuits

Two capacitors of capacitance $C$ and $3C$ are charged to potential difference $V_o$ and $2V_o$ respectively and connected to an inductor, all three in series. Now the switch S is closed. Find the ...
3
votes
3answers
399 views

How do electrons actually move in a circuit?

Last year, we were taught about electricity, about how electrons move in a closed circuit. But as our teacher had not taught us about electric fields yet, she gave us a simplified model of motion of ...
0
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1answer
1k views

Capacitor charging, work done by battery on changing polarity

A uncharged capacitor $C$ is connected to a battery with potential $V$. It becomes fully charged and has a charge $Q=CV$ stored on it. Now the polarity of the battery is reversed. The capacitor will ...
0
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0answers
29 views

What is the form of the skin effect in exponentially decreasing (or exponentially increasing) voltages?

I tried to replicate the standard derivation of the skin effect for exponentially shrinking or growing voltages (idealize the surface of the wire as a half-infinite volume of conductor) but I'm not ...
5
votes
1answer
65 views

How uniquely determined is the impedance of an infinite-chain circuit?

A recent question asked how to find the impedance of an infinite chain of series-plus-parallel circuits. The standard trick is to split the chain after the first link, and treat the tail of the ...
2
votes
5answers
102 views

Why is $R_2$ and $ R_3$ parallel with $R_1$ in this circuit?

I know that if $V_2$ wasn't there it would make sense if $R_2$ and $R_3$ were parallel with each other and in series with $R_1$. Why is it different in this case?
1
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1answer
368 views

How is the current flow perpendicular to the wire?

This answer gives a great explanation of how surface charge builds up to force the current to move perpendicular to the wire: http://physics.stackexchange.com/a/102936/41086 However, it fails to ...
0
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1answer
83 views

Why is the voltage output equal to the voltage drop?

I have a very basic question about measurement of voltage output on some simple circuits. Considering the circuits of the figure: Supposing one wants to measure the voltage output $V_2$, on the ...
2
votes
2answers
49 views

Why does voltage change in series circuit but not in parallel circuit?

Voltage divides after every resistor in series but not when placed in parallel. Please explain this with using very less or no mathematical equations. I have tried searching for an answer online but ...
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votes
1answer
25 views

How is this trigonometric substitution achieved for this simple capacitor circuit equation?

In a simple circuit with one capacitor and one AC source, where the equation of the source voltage is v(t) = Acos(ωt), I was trying to follow how they found the ...
5
votes
2answers
327 views

Modeling stochastic process with frequency-dependent power spectrum

I'm trying to model of Johnson-Nyquist noise propagation in a nonlinear circuit. An ideal (linear) resistor can be modeled very nicely by the Fokker-Planck equation (equivalently, the drift-diffusion ...
0
votes
3answers
110 views

Optimal method for solving circuit

This problem seems quite simple, and I can easily find a way to solve it but the possibility of error in my method is extremely high. This is just a sub-task of a bigger task but this is the only part ...
2
votes
1answer
194 views

Kirchhoff current loop in Resistor Diode Ladder network

I am looking for an approach on how to apply Kirchhoff current / voltage law in the infinitely long diode ladder network. Can anyone help me with this ? I am looking for 1D differential equation or ...