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34 views

Sign of induced EMF and other elements in AC circuit

I am having problems to determine the direction of the induced EMF in AC circuits. For example, we have an inductor of inductance $L$. The induced EMF is given by: $$ \epsilon = - L \frac{di}{dt} $$ ...
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2answers
57 views

Is it possible for an inductor to have a voltage across it without any current passing through it?

When we calculate open circuit voltages for a non ideal transformer . We have current I2 in the right side loop =0 hence the current passing through L3 must be zero but as visible there exists an ...
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1answer
51 views

Mutual capacitance upper limit

I am having trouble making an analog for mutual capacitance from mutual inductance. In circuits with magnetic coupling, there is an upper limit established on mutual inductance due to energy ...
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1answer
50 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 $\mathscr{E}=-L\dfrac{dI}{dt}$. ...
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1answer
59 views

How to model the impedance of a coil with a dielectric slab on the top

I have sketched what I meant in the image below. Were there no dielectric slab, the coil could have been simply modeled as an inductor. But I am not sure what the impedance can be if there is a ...
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1answer
18 views

How do I show for an ideal transformer $M^2=L_1L_2$?

I've been stuck on this problem for about an hour. In an ideal transformer, the same flux passes through all turns of the primary and of the secondary . Show that in this case $M^2=L_1L_2$, where ...
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1answer
60 views

In an RLC series circuit on resonance, how can the voltages over the capacitor and the inductor be larger than the source voltage?

Consider an RLC circuit in series, of the form If the source drives the circuit in AC at the resonance frequency $\omega =1/\sqrt{LC}$, the peak-to-peak voltages on the capacitor and the inductor, ...
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1answer
12 views

Phase angle of a circuit

Above is the problem at hand. I know how to calculate the angular frequency and total impedance of the circuit given the information provided. However, I'm not really sure what the question is ...
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1answer
48 views

Circuit with inductor

How would I find the current through each resistor/inductor as a function of time? I am lost conceptually here. (I made these numbers up, so they may not be "pretty" if/when taking equivalent ...
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1answer
67 views

Confusion regarding inductors

I understand that a change in flux linkages of an inductor results in induced emf across it, the magnitude and direction of which can be determined by Faraday's and Lenz's laws. The magnitude of this ...
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1answer
405 views

Why do we always consider the area of inner solenoid while calculating the mutual inductance of two coaxial solenoids?

While we know that flux linked to an area is the dot product of the area vector of the loop(and not the actual area encountering the field lines) and the magnetic field linked to it, why then do we ...
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1answer
1k views

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 ...
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0answers
39 views

EMF and Distance

As a professional underground service locator, EMF and Inductance are at the very core of what we do. Very few of us truly understand the detailed physics behind what makes it possible for us to ...
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0answers
91 views

Mutual inductance theoretically decreasing while EMF is increasing in 2 square coil system

I have a quick question regarding electricity and magnetism. I am measuring the induced emf in a square coil of wire with an inductance of 439uH (the other coil is also 439uH and is the same shape). I ...
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0answers
29 views

For a straight circular wire, what is the relationship between the self inductance and frequency?

Due to the skin effect, the AC inductance of a straight wire will decrease as frequency increases. Is there any formula that can describe this relationship?
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0answers
44 views

Physical intuition behind the fact that current in an inductor lags behind the emf/voltage by $\frac{\pi}{2}$ in an AC circuit

What exactly is the reason that current through an inductor in an AC circuit acquires maximum value after quarter a time period ($\frac{T}{4}$) of the emf getting the max value?
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0answers
54 views

Resistor and conductor and inductor

What I am gonna to have if: -an inductor is in parallel with a capacitor and all that group is in parallel with a resistor. I know that a capacitor in parallel with an inductor is: ...
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0answers
47 views

Approximate of self-inductance of a square wire coil

Imagine you have a square coil of wires with n turns. In order to calculate the self-inductance coefficient I should know the magnetic field. Is it acceptable to consider the 4 sides as infinitely ...
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0answers
60 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 ...
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0answers
26 views

Image charges for currents?

I am struggling to get my head around a problem involving creating a transmission line using a wire of radius $a$ in a vacuum a distance $d$ above an infinite grounded plate ($d \gg a$). I wish to ...
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0answers
57 views

Mutual inductance versus self inductance of two parallel thin-film wires

I am considering the scenario of two long superconducting thin-film wires (thickness << width << length) running parallel to eachother. They carry a current density that is as usual peaked ...
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0answers
178 views

Internal inductance of the outer conductor of a coaxial cable

Suppose there is a coaxial cable with the inner conductor in $ r < a$, vacuum in $ a<r<b$, and the outer conductor in $b < r < c$, what is the internal inductance of the outer ...
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0answers
72 views

The affect of high frequency and high voltage AC on induction

I am designing an induction system to wirelessly transfer power a short distance. I was planning on using resonant inductive coupling to increase the efficiency. The Inductance of my coil is about ...
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0answers
90 views

Origin of induced emf

What is the origin of induced emf in a conductor which is produced by changing magnetic flux.I mean why changing magnetic flux causes the production of induced emf. Is there some kind of energy ...