All Questions
37
questions
0
votes
3
answers
69
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 ...
- 2,141
1
vote
0
answers
57
views
Static toroidal magnetic field rotating inside toroidal winding
what would happen if I took a toroidal core, generated a static toroidal magnetic field in the core and then rotated the core around it's symmetry axis within a larger stationary toroidal winding ...
- 91
0
votes
0
answers
19
views
Effect of projectile movement inside the coil launcher
I'm simulating a simple coil launcher system where there is a round coil , a capacitor and a round projectile which at first is placed at the start of the coil.
so the whole circuit is a simple RLC ...
1
vote
1
answer
265
views
Does the electric field ($E$ caused by induction) of a moving conductor in a magnetic field drop when connected to a curcuit?
We know that when a conductor moves in a homogenous magnetic field that is perpendicular to itself due to the amount of electric charge gathered on one end of the conductor( as a result of the lorentz ...
0
votes
0
answers
118
views
Back emf for simple DC motor in radial magnetic field
With a basic DC motor setup of a single coil spinning in a linear magnetic field, the back emf produced is a sin wave, as the change in the angle between the plane of the coil and the magnetic field ...
- 135
1
vote
1
answer
164
views
Calculating Induced EMF in Wireless LED Circuit
I have built the following circuit to power a wireless LED and my calculations and measurements do not give the same values. I am measuring a voltage nearly 6 times larger than I would expect in my ...
- 113
1
vote
2
answers
224
views
Doubling the length of a solenoid doubles its inductance. Two identical solenoids in series have up to four times the inductance due to M. Why?
The inductance of a long solenoid with $N_o$ turns and a length $l_o$ is
$$L_o=\pi r^2 \mu_0\frac{N_o^2}{l_o}$$
If I now make a new solenoid, $L_{new}$, with double the length of the original ($l_{new}...
- 1,581
2
votes
2
answers
641
views
INDUCTANCE depends on the number of turns in a solenoid. Is this the case with RELUCTANCE as well?
The total flux ($\Phi$ ) through an solenoidal inductor of length $l$ and $N$ turns is proportional to the current through the inductor and the inductance $L$ of the inductor according to
$$\Phi =L \...
- 1,581
1
vote
0
answers
38
views
Modeling the Effect of Magnetic Induction on Single Neurons
In this paper, the authors suggest a potential mechanism for magnetoreception in birds: as the Earth's magnetic field (taken to be homogeneous over sufficiently small spatial scales) passes through ...
- 359
5
votes
2
answers
766
views
How does electromagnetic induction work on an atomic level?
So far I have come to know that changing magnetic field (or flux) creates current. This is also known as Faraday's law of electromagnetic induction. The direction of the current is opposite to the ...
- 817
2
votes
1
answer
142
views
What is the emf in this circuit?
There is an infinite solenoid with radius $r$ inside the first loop powered by a current that changes over time so that the magnitude of the magnetic field inside the solenoid is $B(t)$. According to ...
- 1,989
0
votes
1
answer
89
views
Induced emf of a moving rod with certain velocity
I am calculating the emf of a moving rod with velocity $v$, given $v$.
My approach is to multiply
$$Blv$$
Where $l$ is the width and $v$ is the rate of change of the length.
But then I found out ...
- 103
0
votes
3
answers
377
views
Why is there no conduction current $i_C$ through a surface between capacitor plates?
The image is from Young and Freedman's University Physics with Modern Physics, Chapter 29 (Electromagnetic Induction).
The image shows a parallel plate capacitor being charged where the current ...
- 155
0
votes
1
answer
156
views
Why is there no EMF induced or flux change of the left ring zero? [closed]
I tried by dividing the system into three parts, and flux is increasing for the left most and right most part and decreasing for middle, but am not able to arrange this in form of a battery, any help ...
1
vote
3
answers
990
views
Induced current in a closed loop in opposing directions
When a magnetic field is given to the loop as in the figure(sorry for the horrible drawing);
I'm told that there will be an anticlockwise current induced in both the 'inner' and 'outer' loops, ...
- 256
3
votes
1
answer
740
views
Explaining how a magnetic field affects currents in a conductor, in the limit of high conductance
Recently, I gave an answer to this question,
explaining my intuition on how much electric field impinges into
a good conductor under certain conditions, in order to reason about the limit of
perfect ...
- 1,379
0
votes
1
answer
119
views
What equation should I use to calculate inductance of a wire coil?
I've been working on a project recently which requires me to build an inductor, however in my research I found many different equations (with a range of variables used and giving very different ...
2
votes
1
answer
290
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 ...
- 21
0
votes
1
answer
245
views
What is the area $A$ in the magnetic flux for AC generator and a coil?
I am getting confused with what area do you use in AC generators and coils.
Let me explain:
in an AC generator, there are two coils that rotate. When using the equation - magnetic flux $= BA\cos(x)$, ...
- 220
0
votes
1
answer
940
views
Is emf equal to or proportional to the rate of change of magnetic flux?
I'm slightly confused about Faraday's law. Is it directly proportional or is it equal to the rate of change flux? If it is proportional, what's the proportionality constant? It might seem like a ...
- 195
2
votes
2
answers
483
views
Energy Conservation: How is Heat generated in a loop with Time Varying Magnetic Field through it?
Consider a circular loop kept in a time-changing magnetic field. We know, via Faraday Law, that EMF is induced across the loop and hence a current appears in the loop. Let there be some Resistance ...
- 1,568
0
votes
2
answers
64
views
What are the basic rules governing the workings of an Inductor? [closed]
To explain my question, I wish to use the case as shown above. I am able to solve the numerical based on the above and similar cases, but still, I have a conceptual doubt regarding the workings of an ...
- 2,517
7
votes
2
answers
860
views
What is the meaning of Potential Difference in presence of Non-Conservative Induced Electric Field?
Case 1
This is a very commonly discussed case in Electromagnetic Induction. In the case above, we need to find out the potential difference across the rod CD, in the presence of time-varying ...
- 2,517
1
vote
2
answers
353
views
Infinite EMF produced in transformer
If I have an ideal lossless transformer, where the ratio of voltages is proportional to the ratio of turns of wire, what, theoretically would stop infinite amplification of the EMF in one coil, and ...
2
votes
0
answers
84
views
How do you apply "flux-rule" in free space?
Faraday's law of induction states that, the tangential component of the force per unit charge$^*$; EMF produced in a loop of wire, is equal to change in the magnetic flux through the loop,
$$\int_C \...
- 455
0
votes
1
answer
512
views
Potential drop across inductors in DC circuits
The potential drop across an inductor is equal to $L(di/dt)$ where $L$ is inductance coefficient. But according to this in a DC circuit there should be no potential drop across the inductor (because $...
0
votes
2
answers
6k
views
Magnetizing inductance in transformer
I asked this question in electronics stack exchange as well but I thought it would also be applicable here as my question revolves largely around Maxwell's equations.
I am learning about transformers ...
- 191
2
votes
2
answers
3k
views
What is total magnetic flux through a coil?
According to Gauss's law of magnetism, the total magnetic flux through a closed surface is zero. But during induction, we study that the magnetic field lines passing through a coil change, as does ...
- 329
1
vote
1
answer
165
views
Don't understand step-down transformer
I think I understand how a step-up transformer works, but don't understand how a step-down transformer converts high voltage AC to low voltage AC. Following the ratio $\frac{V_1}{V_2}=\frac{N_1}{N_2}$...
- 165
2
votes
2
answers
17k
views
How doI find the average induced emf in a coil given the rate of change of flux density, and the area of the coil?
The magnetic flux density changes from +10 T to -10T in 5 seconds. The area of the coil is 2.5 m^2. What is the average emf induced?
By Faraday's law, this will be equal to the change in magnetic ...
- 254
2
votes
2
answers
109
views
Inductor circuit
Consider a inductor circuit with an inductor connected to a DC battery and a switch. Initially the switch is open.
At time $t=0$ the switch is closed. What will happen to the inductor just after the ...
- 21
2
votes
5
answers
5k
views
Can pulsating DC current be transformed?
Since pulsating DC current is changing, why doesn't it induce a changing magnetic flux in the transformer core? Is it able to induce a transformed current in the secondary coil?
- 91
8
votes
6
answers
2k
views
How does an inductor store magnetic energy?
I am trying to figure out what the potential energy of an inductor with a current really means. In a capacitor, the energy stored works like this: if you let the plates attract each other, before ...
- 669
1
vote
1
answer
108
views
Shouldn't the currents be time-continuous here?
My intuition is that the current upon an inductor (say, a solenoid) will always be time-continuous, without "sudden changes". But below is a case that seemingly contradicts this point of view.
There ...
- 400
4
votes
2
answers
2k
views
Why is there no induced electric field in the experiment (Faraday's Law)
Below are three circuit diagrams for each of Faraday's experiments that allowed Faraday to come up with Faraday's Law. In Griffiths' Introduction to Electrodynamics Griffiths states (on page 302 of ...
- 518
1
vote
2
answers
396
views
What physical forces allows for electromagnetic induction [duplicate]
In electromagnetic induction, what force is actually doing the work? what physical force actually drives the electrons around the circuit?
Let's say we have a coil and an increasing magnetic field ...
- 815
4
votes
2
answers
3k
views
Cause of electromagnetic induction?
The rate of change of magnetic flux through a surface (open) is related with the line integral over the closed loop binding the selected surface by one of the Maxwell's equation. But that means even ...
- 3,148