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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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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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40 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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29 views

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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Best method for determining tolerances based on production data [migrated]

Say I am producing a wound coil which is ultimately going to be used in a colpitt's oscillator circuit. I measure the Ls and Rs of the coil, and then install it in a ferrite and then test it in the ...
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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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39 views

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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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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Speed problem in inductance calculus

I made following two routines to calculate mutual inductance of coils in the same axis. The first uses the first and second kind elliptic integrals (uses boost or C++16) and the second uses AGM ...
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1answer
43 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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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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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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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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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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1answer
58 views

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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29 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 +...
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Magnetic field of a solenoid

Why, when explaining the magnetic field of a solenoid, are the individual "quasi-rings" split up into two layers with opposite direction of current (see attached pictures; where the x-es and the dots ...
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2answers
113 views

How do we understand L C Oscillations (Inductor - Capacitor Circuit Oscillation) Intuitively?

How do we understand L C Oscillations (Inductor - Capacitor Circuit Oscillation) Intuitively? How to intuitively understand the Phase Lag and Imagine What is happening in the circuit exactly without ...
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1answer
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Potential difference across the strips of an inductor [closed]

The voltage across the ends of an inductor is $L (di/dt)$. Applying the loop law $V = L(di/dt)$, so the voltage across the strips at a distance x measured from the "LEFT END" should be $V \frac xl$ ...
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Interaction between a current-driven coil and a second passive coil in the same space

Good evening,I have some doubts about mutual inductance. I hope that somebody will be willing to reply to my questions. We have a coil L1 traversed by a current I1. If the current is stationary, L1 ...
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What is the speed of rotation of the magnetic field of a solenoid or current-carrying WIRE

How does one find the speed of rotation of the magnetic field around a current-carrying wire? or How fast is it circulating around the wire? How does one identify the speed of rotation of the ...
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Can inductance be dependent on direction in plasmas?

Inductance is given by the ratio of magnetic flux to the current. For a given plasma at a particular density and temperature (which itself could be a tensor), one may define $$L = {\Phi(i) \over i},$$ ...
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147 views

Magnetic Flux conservation

My teacher said that after switch is shifted (after very long time), $\phi_i = \phi_f$ $\implies i_oL = i3L \implies i = \dfrac{i_o}{3} $ where $i_o$ is $\dfrac{\varepsilon}{R}$ So the initial ...
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Sudden removal of core of an electromagnet

Imagine we have an electromagnet with a soft iron core running 1 A producing a magnetic field strength of 1 T (relative permeability of the core is around 10,000), also assume the wires have ...
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2answers
58 views

Resistance of an inductor in direct current

In a multiple choice question a simple circuit of only a battery and an inductor the length of the inductor is doubled. The question is how does the velocity of the electrons change. Big spoiler alert:...
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1answer
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voltage drop of LC filter in reverse

Two questions that are probably really simple to others. If we are to measure the voltage drop across the capacitor, the same way the circuit above is usually used as an LC filter, we would get the ...
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Are EMF and inductor in parallel or in series in a pure inductor circuit

How can we say whether the applied emf and the inductor in the the image are in parallel or in series? In some discussions I have seen people taking the applied emf and inductor to be in parallel and ...
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Inductances, open switch, arcing: What maintains the arc? EMF source or circuit inductance?

As we know, with an inductance in circuit, arcing will happen at switch contacts while opening the switch. The arc is created because of the circuit inductance. My question is - what will maintain ...
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51 views

Inductors problem

In figure, the switch is in the position 1 for a long time. Then the switch is shifted to position 2 at $t=0$. At this instant, the value of $i_1$ and $i_2$ is Well I'm confused over what will happen ...
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Is there a potential difference across an inductor [closed]

Walter Lewin in his lectures says but all books and online resources go against him. Who is correct?
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76 views

Light is a high frequency electromagnetic wave. Can an LC oscillation circuit emit visible light? [duplicate]

As we all know, light is a kind of high-frequency electromagnetic waves. Can LC oscillation circuit emit visible light?
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103 views

Paramagnetic material in a coil

If we hold the voltage constant, will (and how) the current through a coil change if we put a paramagnetic material in the coil ?
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55 views

Computing the magnetic field inside an infinite solenoid

I want to compute the magnetic field inside an infinite solenoid. I know how to do this if we suppose that outside the solenoid, the magnetic field is equal to zero. But how do you do this if it ...
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Transformer frequency vs resonant transformer frequency

Why does a lower resonant coupling frequency increase the power transferred in a resonant transformer when non-resonantly coupled transformers have an increase in power transferred with higher ...
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1answer
94 views

Why is the magnitude of induced e.m.f more in an LR circuit at the removal of key?

One of the statements in my book:- "The magnitude of induced e.m.f in an LR circuit ( A circuit connect to a AC source having a resistor and a pure inductor in series) is more at the break of circuit ...
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Discharging a LC(R) Circuit

Reading through my lecure script I encountered this example which I don't quite understand: Given is the following Circuit: At time $t= 0$ the circuit is closed, before that the circuit was open, ...
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1answer
160 views

Magnetic field and electric field close to small signal audio

I have built a very compact tube amplifier. I have a 6VAC/3A supply powering the vacuum tube heaters. The 2 wires (positive & return current) are very close to the input. The input signal is very ...
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1answer
90 views

Why is the magnetic flux proportional to the current (Inductance)?

I'm trying to understand the reasoning behing this formula, or how to get there, if possible, using Maxwell's equations: $$\Phi_i = L_i I_i + M_{ij} I_j$$ From the wikipedia page of inductance I got ...
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66 views

In RLC circuit, if source voltage $V(t)=V_p \sin(\omega t)$ then $V_p= \sqrt{V_{R,p}^2+(V_{L,p}-V_{C,p})^2}$?

Consider an RLC circuit,$\hspace{200px}$,and let $V_p$ be the amplitude of voltage from alternating current source,$$ V\left(t\right)~=~V_p \sin{\left(\omega t\right)} \,.$$In addition, let $V_{p,\,\...
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Mutual inductance in a $p$ pole machine

Consider the two single phase motor shown in the following figure. The left/right one is a $2$/$4$ pole machine. The winding of the rotor/stator has been drawn in green/red along with the direction ...
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In series RLC circuit, does decreasing the capacitance value really make the circuit more capacitive circuit?

This seems very counter intuitive to me. How can decreasing the capacitance value make the circuit more capacitive ? The math tells me so : If $C$ decreases then $X_c = \dfrac{1}{\omega C}$ ...
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625 views

Why doesn't the potential difference across an inductor increase over time?

For school, I was trying to solve a question that features a circuit with a resistor, an inductor, and a battery all connected in series. It then shows an increasing concave down graph of something vs....
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68 views

Self Inductor in a circuit

If an self inductor is placed in a circuit and the current is a function of time then where is the emf induced: across the inductor or across the circuit?