# Tagged Questions

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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### 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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### What actually goes on in RLC circuit?

I already have difficulty understanding how each of the RLC circuit elements work individually as it is, and I have no idea how they work simultaneously in an RLC circuit. My schoolbook represents the ...
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### Magnetic field lines opposite to actual direction

I was reading about purely inductive AC circuits. This is how the book tries to explain what happens in each cycle. As it can be seen, in the first and the fourth scenarios ,some magnetic field ...
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### 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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### Capacitor/Inductor Resonance

I am struggling to understand the concept on resonance in electric circuits. I understand that a inductor builds up a charge on it, then the current flows to the capacitor, charging it. But then ...
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### 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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### Inductor potential difference direction

If you have increasing current going down an inductor, the inductor will produce a potential difference to produce a counter current in the opposite direction, or up. The lower potential is then on ...
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### 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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### 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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### alternating current through an inductor

In alternating current through an inductor, why the voltage across the inductor provided by the a.c power supply must be equal to the back emf to maintain the current in the inductor?
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### How to determine the polarities of inductor?

How to determine the polarities of inductor? I know it is determined from Lenz law but most of the time i get a wrong answer,can anyone demonstrate how it is got, through an example?
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### 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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### 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 asking, ...
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### 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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### 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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### 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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### 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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### Finding Inductance in an AC RLC Circuit?

In the laboratory you find an inductor of unknown inductance $L$ and unknown internal resistance $R$. Using a dc ohmmeter, an ac voltmeter of high impedance, a 1 microfarad capacitor, and a 1000 Hz ...
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### Logarithm of the voltage of the inductor in RL circuit experiment is nonlinear with time

I performed an experiment about the RL circuit, with following circuit: (I used the PASCO RLC circuit lab.) By Kirchhoff's voltage law, (denoting the emf of the signal generator $\mathscr E$, ...
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### LCR circuit at resonance

I am studying about the LCR circuit and have a question regarding potential difference across inductor and capacitor. From the thing I have studied I came to know about that potential across inductor ...
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### Current induced in concentric superconducting loops

Suppose you have two superconducting loops, concentric, in a plane. Also suppose that their radii, $R_1$ (outer) and $R_2$ (inner) have the same order of magnitude (so you can't assume $B$ through the ...
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### 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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### 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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### The effects of multi-stranded wire on magnetic field strength

If I were to make a solenoid (with an air core) out of stranded copper wire- say for instance 8 strands- would this effect the magnetic field strength compared to, say, a solenoid with a single stand ...
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### Calculate Temperature change in a solid due to resistive heating

Trying to calculate temperature increase in a solid due to resistive heating by a current flow, is this along the right lines? First I have calculated resistance due to resistivity, then calculated ...
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### Triphasor Problem

Given the data presented in the following link I have to get $R$ for $P = 90~\textrm{kW}$ and the line currents $i_1$, $i_2$ and $i_3$. Any ideas?
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### 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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### 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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### 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: \frac{1}{Z}=\...
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### 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 ...
80 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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### 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 ...
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 conductor?...