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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58 votes
7 answers
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Cyclist's electrical tingling under power lines

It's been happening to me for years. I finally decided to ask users who are better with "practical physics" when I was told that my experience – that I am going to describe momentarily – prove that I ...
Luboš Motl's user avatar
33 votes
10 answers
10k views

What happens to an inductor if the stored energy does not find a path to discharge?

Suppose an inductor is connected to a source and then the source is disconnected. The inductor will have energy stored in the form of magnetic field. But there is no way/path to ground to discharge ...
Alex's user avatar
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21 votes
4 answers
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Derivation of self-inductance of a long wire

Currently I am stuck, trying to derive the self-inductance of a long wire. According to literature it should be $$L=\frac{\mu_r\mu_0l}{8\pi}$$ and in literature its derived by looking at the energy ...
ftiaronsem's user avatar
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20 votes
2 answers
2k views

Does a Mobius resistor have zero inductance? How would you calculate the inductance?

Wikipedia describes a Möbius resistor as follows, and the Patent for this device gives a similar description. A Möbius resistor is an electrical component made up of two conductive surfaces separated ...
Truth's user avatar
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19 votes
2 answers
995 views

Are there analogs to resistance, inductance, capacitance, and memristance connecting the weak force to electromagnetism?

A question was asked over at EE.SE recently which I tried to answer, but much of my answer was speculative. I'm hoping someone here can help my ignorance. In electronics design, there are four ...
Stephen Collings's user avatar
18 votes
3 answers
11k views

Faraday's law - does the induced current's magnetic field affect the change in flux?

I've had this conceptual problem with Faraday's law and inductance for a while now. Take the example of a simple current loop with increasing area in a constant field (as in this answer). So Faraday'...
Martin Ender's user avatar
13 votes
6 answers
18k views

If induced voltage (back-emf) is equal and opposite to applied voltage, what drives the current?

Suppose we have a circuit with a voltage source, a switch open and an inductor all in series. If we close the switch, the potential difference of the voltage source is instantaneously applied to the ...
RuslanM's user avatar
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11 votes
3 answers
9k views

When mutual inductance is occurring between two coils, is self inductance always occurring in each individual coil?

When a coil connected to an AC generator creates an EMF in another nearby coil (mutual inductance), is self inductance simultaneously occurring in both coils?
Sam D20's user avatar
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10 votes
4 answers
4k views

Where does the extra energy come from in an LC circuit?

In an LC circuit, or an LC tank, the capacitor discharges in one direction through an inductor and then the inductor seems to carry energy in the form of a magnetic field , to charge the capacitor ...
physicsnewbie's user avatar
10 votes
2 answers
2k views

Are capacitors and inductors mirror images of each other?

I'm reading through my E&M textbook (Physics for Scientists and Engineers 3rd edition, Knight) and watching as many lectures on YouTube (Shankar, Pomerantz, Lewin, etc) to prepare for next quarter....
jake mckenzie's user avatar
10 votes
3 answers
2k views

Does a thermal inductor exist?

There is an analogy between electric and thermal circuits. A voltage difference is equivalent to a thermal difference. $$\Delta V \equiv \Delta T$$ Electric charge $q$ is equivalent to heat $Q$. ...
P3trus's user avatar
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10 votes
5 answers
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Magnetostatic energy density -- derivation without introducing inductance?

I was looking for a derivation of the expression for the energy density at any point in a static magnetic field. I do know that it is $$u_B=\dfrac {1}{2 \mu_0}\left|\mathbf{B}\right|^2,$$ I was just ...
Avijit's user avatar
  • 625
9 votes
1 answer
9k views

Lagrangian method for an $LC$-Circuit

In the paper http://physics.unipune.ernet.in/~phyed/26.2/File5.pdf, the author solves the LC-circuit using Euler-Lagrange equation. She assumes that the Lagrangian function for the circuit is $$L=T-...
Razor's user avatar
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9 votes
1 answer
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$Q$ factor of parallel RLC circuit in series with a capacitor and resistor

I know that for parallel RLC circuits, the $Q$ factor is given by: $$ Q = R \sqrt {\frac{C}{L}} $$ But now suppose it is connected in series to a resistor $R_2$ and capacitor $C_2$. Would the $Q$ ...
user44840's user avatar
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8 votes
4 answers
7k views

Kirchoff's rules and inductance

Can Kirchoff's loop rule be applied in a scenario involving an inductor? Kirchoff's loop rule states that the closed loop integral $\oint\mathbf{E}\cdot d\mathbf{l}$ is equal to zero. But, in a ...
God's Drunkest Driver's user avatar
8 votes
1 answer
10k views

Why doe we not get a shock on induction cooker?

In induction cooking, eddy currents in cook-pot cause heat to be produced. But why do we not get a shock? Also, why is it that current is converted to heat while it has a good conductor(say, steel) ...
Aadishri's user avatar
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8 votes
1 answer
1k views

Reluctance of torus shaped iron core with embedded wire loop

Imagine a circular wire loop (r = 50mm), the wire has an assumed diameter of zero, which is embedded in a torus shaped iron core with a circular cross-section of R = 10mm. A current in that loop would ...
Robert Seifert's user avatar
7 votes
9 answers
18k views

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 ...
joshuaronis's user avatar
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7 votes
1 answer
523 views

Is Back EMF produced in household wires?

Since we use AC for domestic purpose, shouldn't Back EMF (Counter-EMF) be produced in household wires? If yes, then the output voltage in the appliances will be less (that's what my stupid brain says! ...
Aghila C C's user avatar
7 votes
5 answers
4k views

Is it safe to apply Kirchhoff's voltage law to a closed loop containing an inductance with unsteady current?

Is it safe to apply Kirchhoff's voltage law to a closed loop containing an inductance with unsteady current? If I have a circuit that is just a battery in series with a resistor and an inductor, can I ...
Kamel Isaac's user avatar
6 votes
4 answers
4k views

Inductor and Capacitor with a DC supply

Here is a LC circuit with a DC supply. When the switch is closed at t=0 capacitor behaves as a short circuit while the inductor behaves as an open circuit as the voltage across the inductor ...
Alex's user avatar
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6 votes
3 answers
2k views

Confusion in understanding the behavior of inductor in RL circuit with DC source

When we have a DC voltage source with a switch in series with $RL$ and the switch is closed at $t=0$ then it is said that current is zero initially, but the voltage across inductor is same as that of ...
Trilok Girish Kamagond's user avatar
6 votes
3 answers
4k views

Why do Capacitor Inductor circuits Oscillate instead of reaching equilibrium?

When the capacitor is fully charged there is a potential difference between its poles and that creates a current. This current would create a magnetic field that is changing in the Inductor (because ...
Ulad Kasach's user avatar
6 votes
2 answers
976 views

Why is all of the energy from a battery stored on an inductor but only 50% on a capacitor?

I am learning about inductors and capacitors and we derived the energy stored on a capacitor to be 50% of that delivered by the battery. We did this considering a circuit of a capacitor connected to a ...
Meep's user avatar
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6 votes
1 answer
10k views

Solenoid vs coil of wire

This may sound pretty basic, but: I'm studying for my AP Physics exam, and I am confused. Apparently, the formula for the magnetic field in the center of a loop of wire with $n$ turns is: $B=\frac{\...
George Bentley's user avatar
6 votes
2 answers
7k views

How to calculate required current and specifications for a "wet coil" to generate x Tesla of magnetic field?

A water management project requires a "wet coil" (coil will be submerged in aqueous media) designed to generate a steady-state electromagnetic field of adjustable magnetic magnetic flux density at the ...
Anindo Ghosh's user avatar
6 votes
2 answers
507 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 ...
kthaxt's user avatar
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6 votes
4 answers
2k 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 ...
Shivansh J's user avatar
5 votes
5 answers
2k views

Where does the energy stored in inductor go on opening the switch?

Suppose we have a simple RL circuit. At $t=0$, I close the switch so that current starts flowing in the circuit. When the steady state is achieved, current $i=\frac{\epsilon}{R}$ would be flowing in ...
Nimit Jain's user avatar
5 votes
4 answers
4k views

Why do magnetic coils consist of many thin wires?

Magnetic coils are usually made of thin wire turned into spring shape: Magnetic field which is generated by this solenoid is proportional to the number of turns N. ...
Dims's user avatar
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5 votes
3 answers
4k 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....
kd2amc's user avatar
  • 55
5 votes
3 answers
2k views

Applying Kirchhoff Rule to an LC circuit

In a simple LC circuit (just one capacitor and one inductor), using the Kirchhoff rule has $$\frac{Q}{C} + L\frac{dI}{dt} = 0.$$ But isn't the voltage drop across an inductor $-L\frac{dI}{dt}$? What ...
Yiyang Zhi's user avatar
5 votes
2 answers
23k views

Relationship between inductance and number of turns in a coil in loudspeaker

I am in the process of designing a loudspeaker and have a question regarding the number of turns in the multilayered solenoidal coil and the speaker impedance of $8\:\Omega$. I understand that the ...
user6406's user avatar
5 votes
1 answer
445 views

Current through a solenoid: magnetic field gives a staircase graph

We were running current through a solenoid coil with an iron core, and measuring the resultant magnetic field strength. We expected a purely linear relation for the "current-field strength" ...
Valdemar's user avatar
4 votes
5 answers
2k views

Why complex numbers are used in electronics? [duplicate]

The impedance of a capacitor or an inductor is imaginary. How do we know these quantities are imaginary?
curiousmann's user avatar
4 votes
4 answers
1k views

How does current flow in a purely inductive circuit if the net voltage is zero?

Considering the equation, $$E=−L\frac{di}{dt}$$ The negative sign in the above equation indicates that the induced emf opposes the battery's emf. If we're talking about a purely inductive circuit, the ...
sachin's user avatar
  • 356
4 votes
2 answers
346 views

What does the metres squared represent in the dipole moment?

If I were to do an experiment measuring the magnetic field strength (in tesla) of an iron core solenoid magnet, how would I determine the value for the dipole moment in the formula displayed in https:/...
Altidias's user avatar
4 votes
4 answers
2k views

What are the practical use of LC oscillations?

I understand how energy is transferred between the capacitor and the inductor in an LC circuit, but I am not sure what are the practical applications. Could someone please help?
user31058's user avatar
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4 votes
5 answers
49k views

What is the difference between electromagnet and solenoid?

What is the difference between electromagnet and solenoid? Both these terms seem as the same thing to me. The only difference that I can find seems to be that an electromagnet contains a soft iron ...
user3182445's user avatar
4 votes
2 answers
6k views

Magnetic moment of an iron-core solenoid

I'm currently developing a Simulink model for the attitude control system (ACS) of an undergrad-developed CubeSat. The ACS uses magnetorquers for attitude actuation. The magnetorquers are iron-nickel ...
Synchrondyne's user avatar
4 votes
2 answers
5k views

What is zero impedance in AC circuit?

If a capacitor is connected with an inductor, then because $$Z=\frac{1}{j\omega C}+j\omega L,$$ the Z may be zero. Does that mean when I apply a voltage, the current will be infinite large? What's ...
Xiangru Lian's user avatar
4 votes
4 answers
15k views

Current in inductor just after switch is closed

I have read that the current in an inductor resistor circuit just after closing the switch is zero. This is derived by finding the differential equation in terms of current by using KVL. Is this true ...
user1825567's user avatar
4 votes
1 answer
294 views

Why can voltages be summed around a circuit if there is magnetic induction?

So there is this class I'm attending on Electronic Instrumentation which involves mostly circuit analysis. For example, RCL circuits, and circuits that also contain opamps, transistors, diodes, etc. ...
Jelle 3.0's user avatar
  • 115
4 votes
5 answers
2k views

Why does inductor current lag the applied voltage at its terminal by 90 degrees?

I studied electromagnetism and I am currently working with Inductors. I could not figure out the physical reason based on electromagnetics on why inductor current lags the applied voltage by 90 ...
VKJ's user avatar
  • 273
4 votes
4 answers
4k views

Why is neper frequency called a frequency?

In the context of complex frequency of RLC circuits, the real part is called neper frequency, according to units it's understandable that it has 1/s as the unit which is same as frequency but what is ...
Trilok Girish Kamagond's user avatar
4 votes
2 answers
3k views

Why does the current increase in an LC circuit while the capacitor is being discharged?

From the maths governing an LC circuit (eg. $E_B=\frac{LI^2}{2}$) we can deduce, that the current through the inductor will have a maximum value, when there's no energy stored in the capacitor, or ...
neverneve's user avatar
  • 763
4 votes
1 answer
48k views

Magnetic field due to a coil of N turns and a solenoid [duplicate]

I have learnt that the formula for calculating the magnetic field at the centre of a current-carrying coil of $N$ turns is:- $$ B = \frac {\mu N I}{2r}$$ (where $r=$ radius of the loop, $I=$ current ...
HeWhoMustBeNamed's user avatar
4 votes
1 answer
2k views

Why is parasitic capacitance in inductor said to be in parallel?

Internal resistance of inductance (or other devices) are said to be in series. But parasitic capacitance is said to be in parallel (in case of an inductor). Why is that so? What determines whether an ...
karthikeyan's user avatar
  • 1,161
4 votes
1 answer
10k views

Effective resistance of inductor

In a lab experiment, we connected a simple circuit: an AC voltage source, connected (in series) to a variable resistor and an inductor. We measured the current in the circuit, and the voltage that ...
Ofir's user avatar
  • 125
4 votes
1 answer
63 views

Why In the following $RL$ circuit, the connection to $b$ must actually be made an instant before the connection to $a$ Is broken? [duplicate]

In Resnick halliday, student 10th edition page - 795. In the topic current decay in RL circuit, the following statement is used, the connection to b must actually be made an instant before the ...
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