All Questions
26
questions
0
votes
3
answers
49
views
What happens to the charges in an inductor when you induce a voltage?
Say you have two inductors, and - very much like a transformer - you connect the first one to a voltage source, then place the other one close to it, so that there will be an emf induced by the change ...
1
vote
1
answer
58
views
Does the presence of a disconnected coil nearby affect the self-inductance of a coil under test?
Picture two coils in close proximity. They have the same dimensions and are located co-axially, with a small gap between then (like Helmholtz coils, but much closer together than in the standard ...
- 111
0
votes
0
answers
49
views
Finding the Magnetic Field within a solenoid
So, I have to find the magnetic field within a solenoid such that the field at a point(on axis) is half than that it would be at the centre. Length of the solenoid is 20cm and the current through it ...
- 11
0
votes
0
answers
23
views
Magnetic Field Lines in a Circular Solenoid
We know about magnetic field lines in a circular loop and a solenoid. While studying them, I thought about how the magnetic field lines would be in a solenoid made circular by bending, forming ...
- 1
1
vote
1
answer
288
views
Is this an accurate equation for describing the magnetic force exerted by a solenoid on a ferromagnetic material?
I saw this question, which contained an equation describing the strength of a solenoid:
$$F = (NI)^2\mu_0\frac{\text{A}}{2g^2}$$
where:
$$F$$ is the force the solenoid exerts on a ferromagnetic ...
- 11
7
votes
1
answer
538
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! ...
- 93
0
votes
0
answers
36
views
Are Idealized Transformers Realizable?
Since parasitic capacitance in an inductor is always in parallel with its inductance, would this effectively become analogous to magnetic remanence exhibited within rebars (made from carbon steel) ...
- 1
0
votes
1
answer
2k
views
When an iron core is placed in a solenoid, why does the current increase? [closed]
Does the flux of the coil cut the soft iron core and generate emf in it? I am confused over the fact that since a stronger magnetic field, shouldn't the current increase. I believe the decrease in ...
1
vote
2
answers
144
views
Inductor with ac supply
When an ac source is connected with an inductor we have a continuous change in voltage and current across the inductor.
According to farady and lenz law we will get an equal and opposite voltage ...
- 1,441
0
votes
3
answers
518
views
Phase difference between source voltage and inductor voltage
What will be the phase difference between the source voltage and the inductor voltage? Will the two voltages be in phase or will be out of phase. How much out of phase they will be?
Note that there ...
- 1,441
2
votes
2
answers
892
views
Finding electric potential via direction of EMF
I was trying to solve this question:
I understand that if the current is increasing leftward, then via Lenz's Law, the direction of the induced EMF will be to the right. Given that I now know the ...
- 137
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votes
1
answer
1k
views
Variation of induced electric field with distance
Let's say we have a cylindrical uniform magnetic field which is varying with time at a constant rate. As the distance from axis increases, induced electric field or electromotive force (EMF) varies as ...
2
votes
2
answers
6k
views
why does adding loops in a straight wire increase the magnetic field?
I have seen heaps of articles about what happens to the coil and the magnetic field but nothing about why exactly the overall magnetic field increases when loops are added to a straight wire to ...
- 21
2
votes
1
answer
142
views
Does there exist a rigorous general mathematical proof for $M <\sqrt{L_1L_2}$?
Does there exist a rigorous general mathematical proof for $M <\sqrt{L_1L_2}$? Here $M$ is the mutual inductance between two conductors and $L_1$ and $L_2$ are their respective self-inductances. (...
- 261
1
vote
1
answer
123
views
No inductor - any induced EMF when switch flipped on?
My instructor put in the notes a picture of a loop without an inductor -
just a battery with voltage $\epsilon$, a switch, and resistor with resistance $R$. He explains that as soon as the switch is ...
- 1,177
0
votes
1
answer
2k
views
Magnetic field generated pointing upwards, what direction is induced current?
In this Crash Course video, from 5:57 to 6:15, I think the directions are mixed up, but I could be wrong. She says that when moving the magnet into the loop, the generated magnetic field is pointing ...
- 1,177
0
votes
2
answers
889
views
Why can't mutual inductance create perpetual electricity?
Consider the following image.
When the battery is connected then current starts flowing through the primary cicuit and magnetic flux changes through the coil, this causes electricity to be induced in ...
- 378
1
vote
1
answer
64
views
Can two transformers used to make tesla coils?
Tesla coils seem to perform the same as a transformers: they use two coils and use magnetic field to transfer the energy. Doesn't using two transformers produce the same result? It doesn't seem to be ...
- 31
2
votes
2
answers
563
views
Why do old transformers make sounds, but new ones don't?
What I think is that maybe insulation is gradually removed between plates, and eddy currents start passing from one plate to another and this produces sound. Am I right?
- 71
1
vote
3
answers
1k
views
Current through two inductors after a long time
I'm having trouble with visualizing the following problem, which is asking me for the final, steady current in both inductors $L_{1}$ and $L_{2}$. I was thinking that after a long time, essentially ...
- 111
1
vote
1
answer
1k
views
Energy in a Solenoid?
Consider a circuit consisting of a battery, a resistor and a solenoid inductor. Then, the emf $\mathcal{E}$, is defined as:
$$\mathcal{E} = L\frac{di}{dt} + iR$$
Multiplying both sides by $i$ gives:
$$...
- 2,009
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?
- 545
2
votes
1
answer
503
views
Inductor rise time and inductor wire length
So here is an interesting question about inductors or coils in general.
Suppose you had a inductor which was 12 inch's in diameter and say 12 inch's in length and has 100 turns of wire. The total ...
- 23
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 ...
- 163
1
vote
1
answer
784
views
Non-conservative Electric Field
I was watching this video from Walter Lewin and while watching these two videos, I noticed there is a "contradiction" in what he is doing. All links direct you exactly to where he begins, so you don't ...
- 937
2
votes
1
answer
408
views
Practical physics: where does this current come from?
It's been a while since school and I don't remember the right laws and formulas. So I come here. :)
I've got a power cord extender running from the wall outlet to my washing machine. It's about 3 or ...
- 3,101