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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Calculating the internal inductance of a long wire without the concept of flux linkage

I did read the following questions: "Flux linkage inside of a conductor", "Derivation of self-inductance of a long wire" and "Trouble understanding fractional flux linkage" The answers to them are ...
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Thought experiment: EM fields and coils

Hello Physics Exchange, I have been thinking a lot lately about EM fields. I thought about something the other day and wanted to check with the experts if my intuition is correct or not. I know this ...
44 views

Maximum Impedance for LCR series circuit

Impedance of an LCR series circuit can be maximum when either Inductive Reactance or Capacitive Reactance is maximum at an instant of time. Max Capacitive Reactance is at minimum frequency, and max ...
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Which of these is the right way to interpret finding the current across a coil

If we have a coil which has a resistance of 100 ohms an induced emf of say 20V and this is connected to an AC power source of 100V and is in a series connection with another resistor of lets say 50 ...
9 views

Self-induction in a permanent magnet

when a permanent magnet is moved in a coil, an emf is induced in the coil. so is an emf also induced in the magnet itself? and if not then why not. and if I replace this permanent magnet with a ...
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Why doesn't current flow stop in LC oscillation?

Why doesn't current flow stop in a LC circuit? It is supposed to stop when the magnitude of emf developed across capacitor is the same as the inductor, right?
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What logic is being used in Bleaney & Bleaney to prove the reciprocity theorem for mutual inductance?

I'm currently reading Bleaney & Bleaney 3rd Ed. On pg 136 they discuss the case of 2 coils. Their logic is as follows: If a second coil is brought near to a coil carrying a current $I_1$, there ...
31 views

What does "90 degrees ahead of phase" mean in inductance problems?

I've been working on this homework problem and I have determined that the induced EMF on the right coil is sin(x-90). However, I do not understand what "ahead of phase means." When I graph ...
1 vote
522 views

What is the $B$-field on the axis of a finite Iron-Core Solenoid, a Given Distance Beyond The Tip?

I am building a solenoid electromagnet with a core of known permeability $\mu$. The core needs to stick out slightly beyond the ends of the coils. Let's assume that the magnet is oriented with its ...
1 vote
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Ewing's Molecular Theory of Magnetism & Induction Cookers

This question regards Ewing's molecular theory of magnetism. I.) Ewing's molecular theory of magnetism describes every magnetic substance as being a collection of dipoles that are initially in a state ...
284 views

Resonance frequency with metal

I've made an experiment with resonance frequency of a LC circuit. One part was to place a metal (I think iron) in the middle of the induktivity of LC circuit. I measured a higher resonance frequncy as ...
1 vote
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Coilgun projectile force calculation

Please excuse me if I am completely wrong because I am a 9th grader but I hopefully am able to explain briefly about my problem. I was trying to create a function to calculate the Force of an iron ...
65 views

Are there losses in an ideal transformer?

In a circuit with an AV power source $V$ and a zero-resistance ideal coil, the power from the source. $P_{in} = IV$ is equal to the rate of change in the magnetic energy $U_B$ stored in the coil. The ...
259 views

Predicting voltages in RLC series circuits from AC source: differences in order?

Hoping this isn't too homework-like, but I'm missing some sort of concept here. Doing a lab, and I have to use previous data to predict the voltage across the 2nd and 3rd elements (e.g. order is LCR, ...
395 views

Why is the flux not zero here (Faraday's law)?

I've recently been reading the Griffiths Electrodynamics book, and came across this problem (7.17, 4th edition) and its solution: I don't have any objections for the solution to part a). I have, ...
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Which properties of a metal can be measured via an Inductor in an $RLC$ circuit?

I am trying to understand the properties of metals by using them as cores for an inductor in an $RLC$ circuit. Now the resistivity, saturation point, magnetic permeability electric permittivity all ...
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Is AC voltage across transformer pi shifted?

Suppose the voltage in the primary coil in a capacitor be Vprimary = Vosin(wt) According to my understanding, as the (AC) current in the circuit increases, the Magnetic flux across the secondary ...
363 views

Back emf in an Inductor with an A.C supply

If a pure inductor is supplied with an AC voltage we will always have AC current and time changing electric field in the circuit. That always changing electricfield will cause changing magnetic field ...
1k views

Motion of a magnet inside a solenoid

I have a homework problem where a bar magnet is placed halfway inside a horizontal solenoid. A cut away shows that the magnet's north pole points to the left of the page and the south pole is outside ...
1 vote
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Does parasitic capacitance contribute to the magnetic flux?

When modeling a real inductor, typically the equivalent circuit is the following one: Source A series resistance and parallel capacitor is added. This model works very well to explain the following ...
1 vote
205 views

What does an induced emf do to a loop of varying current?

I know that the magnetic flux through a loop in space is proportional to the current such that $\Phi=LI$. Therefore a change in magnetic flux will produce an emf, so $\mathscr{E}=-L\dfrac{dI}{dt}$. ...
19 views

Does the temperature of a transformer affect the relationship between the induced voltage and primary current?

I'm doing an experiment involving inductance between two coaxial solenoids of the same length where I measure the rms value of the alternating current through the outer solenoid and rms value of the ...
481 views

RL circuit with AC source transient

I have a simulation of RL circuit connected with an ac source. Any one can tell me please that why the peak of the current during the first positive half cycle is higher than the peak of current ...
1k views

How Are Electromagnetic Waves Produced?

How EM waves are produced say by a capacitor of an LC circuit here if $E$ is increasing in upward direction? My thoughts Thought 1:- If E is increasing E flux is increasing thus B field must be ...
272 views

Mutual inductance - induced magnetic flux in the primary

Let there be two coils, L1 (with self inductance L1), and L2, with self inductance L2. The first coil is connected to a sinusoidal supply, and the second one is connected to a resistor load, as shown ...
3k views

Voltage drop across an inductor in a $RL$ circuit

for a circuit that has a resistor (resistance $R$), and a inductor (inductance $L$), that are connected in series to a source of AC electromotance. How do I find the voltage drop across the inductor ...
105 views

Magnetic field in a capacitor in a $LC$ circuit

Consider a simple $LC$ circuit in which the charge on the capacitor varies sinusoidally. Current flows in this circuit, changing the charge on the capacitor and hence changing the electric field ...
1 vote
256 views

Inductance of a toroidal electromagnet with a gap

Suppose we have a toroidal electromagnet of length $l$ and section $A\ll d^2$, with an air gap of width $h\ll d$ with a wire turned $N$ times around it. Suppose we also know that for a large interval ...
74 views

Why actually at resonance the inductive and capacitive reactance cancel each other?

I am learning about series LC circuit that is in resonance. It says it is when the impedance offered is minimum due to the angular frequency being at a particular value(1/√LC).People say that they are ...
99 views

Why current does not instantly reach maximum value in an $LR$ circuit?

In an $LR$ circuit, I read that when an resistor $R$ and an Inductor $L$ are connected to an emf $E$ source in series, and the switch is switched on, the current flowing in the circuit does not ...
11k views

Calculating magnetic field strength for a very small electromagnet

I am trying to calculate the magnetic field (in tesla/gauss) of an electromagnet that is very small and has very few windings. For example 12 windings over 0.003 meters. I know this is not going to ...
381 views

Apply Kirchoff Law to an $LC$ circuit (no battery)

In the image above, I understand the current is moving clockise. I was attempting to apply Kirchoff Rule which for an RLC circuit is but I wanted to confirm that $V_s$ is zero in this scenario such ...
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Confused about sign of mutually induced EMF when applying KVL

Suppose I have several circuits with inductors like so: and I want to find the current $i_1, i_2, i_3$ in each circuit. I will use Faraday's law to find the induced EMF and then use Kirchhoff's ...
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How to find magnetic permeability of a mixed core?

Inserting a ferromagnetic rod into the core of an inductor increases its inductance. If the change in inductance is known, the following equation can be used (or so I assume) to find the relative ...
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Calculation of self-inductance of an arbitrary shape

I have been taught two methods for doing this however I do not understand one of them completely. I will try to explain what I don't understand with a few examples. Irodov 3.319: A long coaxial cable ...
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How to calculate impedance in a wire moving through a magnetic field?

I'm trying to build a homemade rail accelerator. I understand that the force on a wire is proportional to the cross product of the magnetic field vector and the current vector. I asked my professor ...
238 views

Energy Stored In Superconductor

I have two questions regarding this topic: What is the equation to calculate the energy stored in a superconductor when you apply a current. I’ve been looking it up and have been getting ...
1 vote
261 views

Does the unit "volt-seconds" have any interesting interpretation?

I was contemplating the units of capacitance and inductance in electrical circuit theory and noticed something that bugs me. Although there are many equivalent ways to write the farad (seconds per ohm,...
The following video here derives an equation for the reactance of a capacitor. I am trying to derive the equation for reactance of an inductor. Given an AC voltage drop $V(t)=V_osin (\omega t)$ in ...