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Questions tagged [inductance]

The property of an electrical conductor through which a change in current through it induces an electromotive force in both the conductor itself as well as in any nearby conductors by mutual inductance. Also use more broadly for electromagnetic phenomena in solenoids.

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Understanding simple LC circuits

I'm trying understand the physics of simple inductor-capacitor circuits such that there is just an inductor L and a cacpacitor C and a switch. Imagine first that the capacitor is fully charged and ...
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Conceptually understanding RL circuits

I'm struggling to conceptually understand the current-time profile of an RL circuit. Specifically, what causes the rate of change of current, $\frac{\partial i}{\partial t}$, to start off high when ...
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Some confusion regarding RLC circuits

I'm a mathematics student, and it has been years since I last did current/voltage/resistor related subjects in high school. However, for one problem that I've encountered, I actually need to calculate ...
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Trouble understanding fractional flux linkage

My question is quite similar to one in the link: Flux linkage inside of a conductor. But I have trouble understanding any of the answers provided there. Specifically my question is the following: I ...
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Force vs Stroke for Open-ended Solenoid

If I understand correctly, the force (F) versus stroke (x) curve for a solenoid which is open ended (there is no plunger stop in the middle) is something like the curve below: The plunger is forced ...
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How would you find the time taken for a steady current for a superconductor?

For part (c) I need to find the time taken for the solenoid to gain maximum magnetic field strength. However, since it uses superconducting wires, the total resistance is zero, so how would I be able ...
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Electromagnetism question about the magnetic flux and inductance of a parallel wire transmission line

I derived using the formula for the magnetic field of an infinite wire that the flux between the wires is the same as that in the answer but with $b-a$ on top. This is because when you integrate $B\...
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1answer
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Inductor behaviour in LC oscillation [closed]

I want to ask that in LC oscillation , when the capacitor is discharging then on other side the current is increasing in inductor do inductor should act means it should oppose the current ....as same ...
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Why current flows in an inductor?

If during self-induction the inductor produces a current in opposite direction of that of battery in order to resist the change of current through it then how could the current after some reasonable ...
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Simplifying electrical circuits [migrated]

I have looked everywhere, but i can't seem to find a way to simplify this circuit. I wish i could tell you some of my ideas, but i'm really lost here, can someone help me? If you could explain how to ...
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1answer
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Phase difference

Is there a phase difference between the magnetic field and the current producing this field? I have simulation results for three-phase transformer at different frequencies. The spectrum of the ...
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Turn density impact on B Flux

I am messing around with electromagnets and I am actually making my own winding them by hand. The equations that are used to calculate magnetic field strength do not really have a geometry term in ...
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1answer
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Why is the information of a time delay missing in formulae of voltage drop across elements when we emulate DC with an AC voltage supply?

In an AC circuit, the reactance of capacitive and inductive elements are determined by the frequency of the AC signal. When we try to emulate DC analysis by putting $\omega$ = 0 , the capacitive ...
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1answer
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Why does a conducting cylinder spin when held next to a conducting ring around a solenoid?

My uncle showed me this video. I understand that the magnetic field from the solenoid induces a current perpendicular to it in the ring. However, I don't see why this current would result in a torque ...
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Energy stored in an inductor [duplicate]

When we place an inductor in a circuit it opposes the change in current in that circuit. For increasing current in that circuit some work needs to be done against the inductor. This amount of work ...
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1answer
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LCR circuit (AC source) potential difference across capacitor

For a LCR circuit connected to AC source of emf$$E= e\sin(ωt)$$ and let the current in LCR circuit be I then $$I=i*\sin(ωt+Φ)$$ then it is given that potential drop across the capacitor is V.ie$$V=-...
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What is causing the current sinusoidal delay regarding voltage in inductive circuits? [duplicate]

Do electrons acquire some electromagnetic 'mass'as they have so much slow acceleration in the coil due to obviousely electromagnetic field acting on them or it is just the net voltage that drops down ...
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Why does inductor current lag the applied voltage at its terminal by 90 degrees?

I studied electromagnetism and I am currently working with Inductors. I could not figure out the physical reason based on electromagnetics on why inductor current lags the applied voltage by 90 ...
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Concept of Flux Linkage in solving Faraday's Law Problems

I understand that the definition of flux linkage as kind of the sum of all the fluxes going through the surfaces bound by all the turns. That is, $\Lambda = N \Phi $. However what I don't understand ...
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3answers
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Current in only inductive AC circuit

Current through a LR circuit is given by $$i=i_0 (1-e^{\frac{-tR}{L}})..1$$From here I can observe that as I tend R towards 0 no current flows through the circuit , and current will be 0 when the ...
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1answer
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Mutual inductance circuit analysis

given the following circuit, I need to find $ I_1(t) $ and $ I_2(t) $ (forgive my microsoft paint skills ;) ) I've come up with a solution, and I wish to check with you if it is current or, ...
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AC currents for self-inductance of a wire

I've been currently reading some stuff on self-inductance of a wire. There are different regimes where different approximations are used. For the AC currents the notes state that an approximation can ...
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2answers
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Why to use non-inductive resistances in Callendar-Griffiths bridge?

Worsnop in his Advanced Practical Physics for Students states that All the resistances should be 'non-inductive', for in this method it will be seen that the galvanometer is permanently connected ...
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Applying Kirchhoff Rule to an LC circuit

In a simple LC circuit (just one capacitor and one inductor), using the Kirchhoff rule has $$\frac{Q}{C} + L\frac{dI}{dt} = 0.$$ But isn't the voltage drop across an inductor $-L\frac{dI}{dt}$? What ...
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Why does self-inductance still allow variation of current in circuit?

Taking a solenoid as an example, when constant current $i$ is passed through the solenoid constant flux is seen. But when the current starts to vary, the magnetic field created by a changing current ...
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Is the flow of charges in inductor though electric field zero?

How electric field inside the wire of an inductor is zero (i.e. material of which loop is made — note material is assumed to be a superconductor), then how electrons flow in an inductor if electric ...
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1answer
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How is the rate of current change in an inductor present in a circuit maintained / decreased?

Considering an ideal circuit of DC voltage source and an inductor connected together with a switch in between them. When the switch is closed at t=0 the current starts increasing which causes induced ...
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1answer
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Why is neper frequency called a frequency?

In the context of complex frequency of RLC circuits, the real part is called neper frequency, according to units it's understandable that it has 1/s as the unit which is same as frequency but what is ...
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Confusion in understanding the behavior of inductor in RL circuit with DC source

When we have a DC voltage source with a switch in series with $RL$ and the switch is closed at $t=0$ then it is said that current is zero initially, but the voltage across inductor is same as that of ...
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1answer
72 views

Inductance of parallel wires with parallel and antiparallel running currents

The well-documented mutual inductance of a pair of parallel wires with antiparallel running current is $$L=\frac{\mu_0 l}{\pi}\left(\ln{\frac{d}{a}+\frac{1}{4}}\right).$$ This can be thought of as ...
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flux threading through superconducting ring

I have been confused over the wording used in this paper describing RSFQ logic circuits: http://www.mukhanov.com/uploads/LikharevSemenov-RSFQReview_IEEETAS91.pdf From page 6: " If such a single flux ...
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2answers
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Why inductor voltage at $t=0$ is equal to source voltage? [closed]

I am sorry to ask this elementary, fundamental and most repeatedly asked but i have some doubts that were not cleared during my undergrad days. I will try to present my doubts in following points. 1 ...
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1answer
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Why charge induction is limited to some amount?

Polarization occurs when a charge is placed next to a conducting object. When we ground the side of the object opposite the charge, that side becomes neutral. But this neutralization disturbs the ...
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Calculate the force acting on a magnet inside a solenoid wrapped in Iron

Sounds like a simple question, doesn't it? But it isn't and it has been frustrating me to no end. First, my setup is fairly straightforward: I am building an electromagnetic actuator and have a magnet ...
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1answer
55 views

Which method of calculating mutual inductance to use?

I am planning to make a wireless charging device for a school project using coupled induction. However, I have found a few different ways of calculating mutual inductance for coupled solenoids and ...
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1answer
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Why the $L$ in an $RLC$ circuit? [duplicate]

I was studying for a differential equations class and came upon some information about $RLC$ circuits. I know the $R$ stands for resistance (makes sense) and $C$ stands for capacitor (this also makes ...
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Finding the voltage across an inductor when opening the switch [closed]

Well, I've the following circuit: In the circuit I want to find the voltage $\text{V}_{\text{Y}_1}\left(t\right)$ as a function of time, after I open the switch (this switch was closed 'forever' ...
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1answer
36 views

Transient state analysis of RL circuit

A circuit consists of an ideal battery an ideal inductor and zero resistance. The value of inductance is $4$H and the battery has an emf of $2$V. There is fuse in the circuit which breaks after when ...
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2answers
64 views

Impedance of an LCR circuit

So I am trying to understand how to find the impedance of the parallel LC component of this filter circuit. I am given that the transfer function $\mathbf{T}_C = \dfrac{\mathbf{V}_{out}}{\mathbf{V}_{...
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Force on a ferromagnetic rod in a solenoid

I am developing an experiment with a coil-gun/rail-gun and need to run some equations to see what I need to build. The end result is to launch a ferromagnetic rod (iron, or possibly steel) a ...
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42 views

Estimating the effect of inductors in an RL circuit

I'm trying to understand how an inductor works in an RL circuit. When I use an air core inductor, my estimation is fairly accurate to the test circuit but as soon as I use an inductor with a core, the ...
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1answer
33 views

Induced EMF in an inductor

In the above figure, the circuit is closed for a very long time and is then opened. It is stated that "the emf across the inductor just after opening will be very high so as to oppose the change of ...
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4answers
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Inductance in superconducting wires (and the math)

I'm very curious about inductors in general, and how similar they are to capacitors. In the above picture the formula of current over time in an inductor with wire resistance $R$ is written. I'm ...
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2answers
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Current in the inductor at $t=0$

$L_1 = 5H, L_2=0.2H, M=0.5H, R_0=10 Ω$, and $i_g=e^{-10t}-10 A$. I need to find $i_2$. I've started with DE $$i_2R_0+L_2(di_2/dt)+M(di_g/dt)=0$$ and solved it for $i_2$, so $$i_2=0.625e^{-10t}+Ce^{-...
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2answers
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Finding electric potential via direction of EMF

I was trying to solve this question: I understand that if the current is increasing leftward, then via Lenz's Law, the direction of the induced EMF will be to the right. Given that I now know the ...
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$j$-$\omega$ method alternating current circuit help [closed]

I'm suppose to calculate the current and the phase angle. Can someone please tell me if this is the correct solution?
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1answer
105 views

Would Kirchhoff’s rules not hold in this circuit?

On my E&M test I was given the circuit diagram below and asked to find the charge on the capacitor after a long time or as $ t \to \infty $. In class we had used Kirchhoff’s voltage rule on the ...
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1answer
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Is there a historical name for an inductor that starts with the letter $L$? (RL circuits) [closed]

Why is a circuit with a resistor and inductor called an RL circuit and not an RI circuit? Was there a now-obsolete name for an inductor that started with the letter $L$?
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Magnetic field due to a double tape line

I have been asked to calculate the inductance of a double tape line : Now we know that $$ N\phi = LI$$ So let's calculate the magnetic field by assuming an amperian loop like this: $$\int B.dl = ...
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Imaginary Capacitance and Imaginary Inductance interpretation [closed]

Today I came across with Complex Capacitances and Inductances for the first time: $$L(j\omega)=L_{real}+jL_{imaginary}$$ $$C(j\omega)=C_{real}+jC_{imaginary}$$ So I started looking at their meaning. ...