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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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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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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 [on hold]

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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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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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 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 considerable ...
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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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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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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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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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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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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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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. ...
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LCR circuit , impedance, imaginary [duplicate]

What is the physical interpretation in behind impedance of capacitor and inductor? we know that resistance oppose the current in the same direction of voltage. But how capacitor and impedance oppose ...
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Inductor and Capacitor in Parallel

I've been staring at this for 10 minutes and I'm soooo confused. Hopefully, you guys can help! So, let's say we close the switch. From what I understand, the capacitor will charge up to $10V$ almost ...
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Formula for total current and phase angle in function of given currents and phase angles in the branches of a parallel RLC circuit

Consider this parallel RLC circuit powered by an sinusoidal alternating voltage and two branches, one containing an ohmic resistance $R_1$ and a capacity $C$, the other one containing an ohmic ...
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Finding the inductance of a laser given things like wire length, peak power, and peak current

I am operating an RCA GaAs diode laser operating near $904$ nm designed to be in pulse mode. The driver circuit for the pulsed diode laser is below: With the repetition rate of the trigger set at ...
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Why do phasor derivations related to LCR circuits consider $V_c = I * X_c$ even if voltage and current are out of phase?

In a capacitor, the current leads by $\pi/2$. But even then derivations of of total voltage in LCR circuits using phasor diagrams assume that $V_{inst.} = I_{inst.} * X_c$ Where $V_{inst.}$ is the ...
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Adding a capacitor in parallel improves power factor of an inductive circuit?

I know that to reduce power loss during transmission, we require a power factor as close to one as possible. This can be done by making $Z$ tend to $R$ which can be done by increasing $X_c$ such that ...
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Why isn't there any current in the Primary if Secondary circuit is opened in a Transformer?

Assume an ideal transformer, with no load/resistor attached on the Secondary (Open Circuit), it is said that the Primary would act as if it is an open circuit too, thus no current flows through the ...
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LC-circuit and the current

A capacitor and a coil are charged in the LC circuit. When the circuit switch is closed, the current starts to flow. In theory the oscillations and the current do not deteriorate, but why in reality ...
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Differential equations for the LC circuit

On wikipedia one can find that the DE for an LC circuit is given by $$\ddot I+\frac{1}{LC}I=0$$In one of my papers however I found the equation $$\ddot Q+\frac{1}{LC}Q=0$$ and I've been confused by ...
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How can there will be current in purely inductive circuit? [closed]

In a purely inductive circiut there are two emf's one is applied and other is induced applied emf and induced emf are equal and opposite, then how can there will be current in a purely inductive ...
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Does it make any sense to ask for mutual inductance between a wire and a coil?

I have been asked to work out the mutual inductance coefficient between a circular spire of $N=1$ turns and radius $R$ and an infinite wire contained in the plane in which the spire lies. This, ...
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Dissipation of energy in inductors

Please explain the dissipation of energy in a circuit containing a resistance and inductor after the switched in the circuit is opened.I mean how do you explain that the energy that is across inductor ...
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2answers
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Can we define rms current for pure inductive and capacitive ac circuit?

For a purely inductive and capacitive ac(sinusoidally varying) circuit, average power dissipated across a capacitor or an inductor is zero. Then does that mean RMS current is zero?
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Can an Opposing Current Create another Opposing Current?

In Inductors when current increases it's magnetic field induces a voltage which causes an opposing current that slows down the rise of the current that initially creates it, but can this opposing ...
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52 views

Electrons in an Inductor

What basically happens to the electrons, does the magnetic field produced by the electron moving in the inductor affect itself. what are the forces involved? Please elucidate the mathematics. The ...
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Why do we ignore the negative sign of self induction while considering inductors in an AC circuit?

I have been taught that the back EMF in a coil as per Lenz's law is $$ e =-L \frac{di}{dt} $$ Then why is that during circuit analysis of AC circuits, we consider the e across inductors to be $$ ...
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What do the magnetic fields lines produced by a solenoid made out of another solenoid look like?

Suppose we take a solenoid: I was wondering what the magnetic field pattern would look like if the black current-carrying wire in the depicted solenoid was replaced by a solenoid. In other words, ...
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What does 'Oppose a Change in Current' really mean from Lenz Law?

We all know what Lenz Law is, but I have a bit of trouble conceptualizing the phrase above. Does 'Oppose a Change in Current' means it will take more time for the current to increase to its maximum ...
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Electromagnetic Force vs Magnetic Force

I am confused between these two types of forces, what makes them different? For example, a moving ferromagnetic object in a solenoid that moves because of a magnetic field created. Which field would ...
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rotating capacitor question

Imagine a simple setup. I have a copper disc and another copper element held close to the disc at one of it's sides, this element is stationary but the disc is rotating, the part between the disc and ...
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Why do we not have devices like inductors or capacitors to hold gravitational field? [closed]

I know that a capacitor can store electric field and an inductor can store magnetic field. So is there a way that gravitational field field can be stored in any such device. Also we do not have a law ...
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Now what will happen in this circuit?

Consider a circuit as shown in this figure below- Assuming switch S1 is closed such that current flows in loop ABCDE for a long time and steady state is reached. Now, my question is simple, suppose (...
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Why is the integration constant in a purely inductive AC circuit assumed to be zero?

While studying about AC circuits, I came across the usual differential equation of an AC circuit (in which the voltage across the source is a sinusoidal function of time) containing an inductor only. ...
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1answer
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Why is the inductance of ionized air similar to inductance of wire?

Why is inductance of wire which is about 1 microHenry per meter similar to the inductance of air broken down by lightning (where the high voltage of a lightning strike breaks air down and it becomes a ...
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Why don't transformers have capacitors?

I recently learnt about how resonance in an LC (inductor capacitor) circuit could increase the efficiency of the circuit, for application in something like Resonant Inductive Power Transfer. Excuse ...
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110 views

Current as a function of time RL-circuit [closed]

The switch, S, in the circuit has been open for a long time. At t=0 it suddenly closes. Calculate the current through the inductor, $I_L$, as a function of time. Resistance in the inductor can be ...
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58 views

Dot convention inductors in series: what is going on

So I'm really confused with mutual inductors and dot convention. If your answer is going to be a link to any website I can assure I read them all and that only left me more confused. So here are my ...
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1answer
64 views

Inductance in Superconductors

This is a picture I got from a question in this website, it seems totally fine, but if you try looking it gain, is the heater placed in the wrong position? Because as I know current takes the path of ...
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1answer
41 views

Overdamped RLC circuit

I have a series RLC circuit with an equation: $$\frac{d^2I}{dt} + 2\alpha \frac{dI}{dt} + \omega_0^2 I = 0$$ (No outside sources affecting the circuit, only some $I_0$ was in the circuit at the ...
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Is induced EMF proportional to the square of the number of turns of a solenoid?

In order for this question to be clear I must first give some context: Consider a 10cm long solenoid (solenoid A) of radius approximately 1cm with 400 turns. Let the current in $A$, $I_A$, ...
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3answers
269 views

Can Kirchhoff's Voltage Law be applied here?

First, consider a simple circuit comprising of an ideal battery of EMF: E and a single resistor of resistance R. Imagine that the switch is opened in the circuit. In the battery, some internal ...
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Current in circuit after joining two inductors with different currents through them [duplicate]

Let's take two inductors: one has its peak current (say, Io) flowing through itself and the other has no current through itself. Now if these two inductors are joined in series in a closed circuit, ...
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4answers
34 views

Energy and electromotive force in transformers

I just learnt the formula $ε_2=ε_1\frac{N_2}{N_1}$ in relation to transformers. While I understand the mathematics that were used to derive it, I am having difficulty understanding where the extra ...
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Integration in order to derive formulas for self-inductance

When deriving formulas for Self Inductance, I stumbled upon the following integration: $$\frac{V_o}{L}\int_0^tsinωtdt=\int_0^t\frac{dI}{dt}$$ The result logically is: $$-\frac{V_o}{ωL}cosωt +...