Induced Definition and 925 Threads

The Gauss formula for the induced metric reads ##g_{\mu \nu} = G_{ab}\frac{\partial X^a \partial X^b}{\partial x^\mu \partial x^\nu}##, where ##G## is the metric of the embedding space, the capital ##X## are positions in the embedding space, the little ##x## are positions inside the embedded...

I am saying that V1=V2 since the emf induced in the rod is the same for both cases equal BLv. Am I correct?

I just saw a question saying there's an induced current in a dc motor. i always thought dc motors' electromagnetism is separate from the ac generators' electromagnetic induction? if there's really an induced current, how will the overall system work then? wouldn't the rotation be opposed? also...

TL;DR Summary: if there are 2 coils, one with a switch and a battery. If the switch is closed, exactly at that moment when the switch is closed, there is no induced voltage in the other coil, am I correct? In this image, exactly at the moment when we close the switch, there should only be...

this is the figure in the question.The question can be solved by first finding the induced voltage (and then the induced current), and then we can find the force on each side of the wire due to the magnetic field and subtract them from each other (since the force on the upper and lower sides are...

As far as I know, there are two causes of the rotational motion of the charged ring. T he first torque is from Lorentz force: $$T=Q\mathbf{R\times ( v} \times \mathbf{B}_{r}) =-\frac{QR^{2}}{2}\frac{dz}{dt}\frac{d\mathbf{B}_{z}}{dz}$$ (where ##\mathbf{B}_{r}...

Here is a curve of induced emf against time. We know from Faraday's law that E = -N d(phi)dt and due to the negative sign, clearly E and d(phi)/dt must have opposite signs, i.e if E > 0it would not be possible for d(phi)dt > 0, as then -N d(phi)dt = E <0 , when we already defined E >0, clearly a...

A wire loop accelerates from position 1 to position 5. It enters an area of a homogenous non changing magnetic field B. Rank the induced currents in the loop starting from the biggest. in solutions it says I4>I2>I1=I3=I5=0 but i dont understand why

If a current flowing within a loop is interrupted by a switch a spark occurs at some point which is a result of the built up potential across the opening switch contacts due to the stored energy in the magnetic field that was created by the flowing current. But what happens if I have a loop...

I’ve read that the Ca2+ channels in neurons can be manipulated through the use of certain radio wave frequencies. And the resulting internal/external charge differential will cause the neurons to fire. Does anyone have any more insight into that?

The correct answer to this problem is: ##\sigma = \varepsilon_0E\frac{\varepsilon-1}{\varepsilon}## Here is my attempt to solve it, please tell me what is my mistake? ##E_{in} = E_{out} - E_{ind}## ##E_{ind} = E_{out} - E_{in}## ##E_{in} = \frac{E_{out}}{\varepsilon}## ##E_{ind} = E_{out} -...

It didn't work and I don't know how to do it.

TL;DR Summary: A (nonconservative electric field is induced in any region in which) A. there is a changing magnetic flux B. there is a changing magnetic field C. the inductive time constant is large D. the electrical resistance is small E. there is electrical current there can be more than one...

there are a bunch of problems in this section that ask similar questions, but they ask the amplitude and this doesn't. this is an even problem so i do not have the answer, but my hunch is that it is not an amplitude question. i solved for the amplitude so i am guessing i got this one wrong...

Hey guys. Im about to learn about footfall induced vibration. However i want to reach the same results as in the pdf page 44 ''design guide for footfall analysis'' i get 0.000726 while they get 5,79E-0,4. Can anyone help me figure out what im going wrong and where i have made a mistake?

For this part (b) of this problem, The solution is, However, would a better explanation be: As the spheres are conductors, there will be free electrons within and on the surface of the conductors that will be polarized by the external electric field between the conductor. This will decrease...

The context behind my question is quite silly, but I've encountered some people who believe lasers cannot produce explosions, even at insane levels of energy. Now, I'm not big on physics nor will I pretend I am, I think they could but I came here to get a more knowledgable opinion(using a silly...

Given example for what is induced mapping ? In basic level

Model ground effect-vehicle shape like on picture fly above flat surface like floor sports hall or ice, wing end plates and trailing edge is so close to the ground(1mm) we can assume airlfow under the wing is zero and has stagnation pressure("100% ground effect"). How to calculate induced drag...

Hello! Assume I have a 2 level system, where the 2 levels have opposite parity. If I apply an electric field, I will get an induced dipole moment. For now I want to keep it general, so the induced dipole moment can be very large, too. Let's say that I start rotating this electric field in the...

This is usual induced drag diagram. I have 2 questions: From Kutta–Joukowski theorem Fr is always perpendicular to effective airflow. 1. Does it mean for case without effective airflow(zero induced downward velocity), Fr is perpendicular to freestream airflow,so drag is zero? When effective...

Can anyone show me where I'm wrong?

Say we have a long solenoid with a current that is fluctuating in time. Then the changing magnetic flux in the solenoid will induce an electric field around the outside of the solenoid (Faraday's Law). This induced electric field is not conservative and therefore cannot have a corresponding...

So changing magnetic fields induce electric fields (Faraday's law when the magnetic field is changed by either moving the source or by changing the current in the source that's causing the magnetic field, ie. we're not moving the conductor where an emf is induced so there's no f=qvXB). Also...

Faraday's law tell's you about the line intergal of the electric field, but you have to know the direction of the induced electric field first in order to properly apply it. How can I find its direction? Is it in the same direction as the induced current?

This question appeared in a university entrance exam.Basically, if magnetic flux passing through a surface of a loop changes over time ,only then e.m.f will be induced to that loop.But here only a straight line is used and there's no chance of forming any area.So by definition there's no chance...

Hello,everyone! Recently i am doing an experiments about electromagnetic induced transparency in 85rubidum gas. I have two light source,which use the polarization spectrom frequncy stablizaiton technology to make them stable.One is used for probing light,and the other one is used for coupling...

If we have an electromagnetic wave like the one in the picture and a molecule which is, in the image, the small black ball with electron cloud being the part with "minus sign" in it, does the molecule with its cloud start to oscillate, once the EM wave hits it, as an induced electric dipole...

To solve this problem, we need to evaluate the following integral: $$\epsilon = \int_{P}^{C} (\vec v \times \vec B) \vec dl$$ The main problem is, in fact, how do we arrive at it! I can't see why a Electric field arises at the configuration here. The magnetic field of the rotating sphere is...

##\phi_m = Blwcos\theta## voltage = ##\frac{-d\phi_m}{dt} = Blwsin\theta\frac{d\theta}{dt}## where l is the length of the loop and w is the width of the loop The top and bottom of the loop have magnetic forces perpendicular to the loop. My book says that means that there is no current through...

Here is the question: We know the equation \epsilon = \frac{d\phi }{dt} = BAcos(\theta ). This means that the only way we can create an induced voltage is if we change the magnetic field, change the area of the loop in the magnetic field, or change the angle between the normal vector to the...

I am currently working on an experiment that involves dropping a magnet from varying heights and measuring how the induced emf of a solenoid changes as a result. I am currently somewhat struggling with a derivation for a relationship between the two variables, however, this is what I have been...

If we put a positive charge outside of a conductor, there is an induced charge, but if we put a positive and negative charge inside a conductor, there is no induced charge?

The title pretty much covers it. I'm having to calculate the field induced inside the human body by an antenna in the near field (essentially, a phone placed close to a user's head), and I'm drawing a blank on how to relate the field generated by the antenna to the field induced inside the...

Hello! I am analyzing some data from some rotational transitions between 2 electronic energy levels in a diatomic molecule. I noticed that for different runs that covered the same regions, the peaks we observe are shifted with respect to each other when the power of the laser driving the...

Hi, We know that a varying magnetic field creates and induced electric field, and a varying electric field creates an induced magnetic field. If there is a varying electric field (let's say sinusoidal), then this electric field creates an induced magnetic field. And if this produced magnetic...

hi guys our professor asked us to confirm the units of volume charge density ρ and also the surface charge density σ of a dielectric material given by $$ \rho = \frac{-1}{4\pi k} \vec{E}\cdot\;grad(k) $$ $$ \sigma= \frac{-(k-1)}{4\pi} \vec{E_{1}}\cdot\;\vec{n} $$ I am somehow confused about the...

So for the first question it is very straight forward. The magnetic field is going through the loop, increasing the flux through the loop. The induced current must flow clockwise in order to generate a field that goes through the loop in a downward direction to oppose the change.The second...

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I need to find the FEM induced in a coil that rotates around the y-axis and is inside a solenoid. The coil starts in the plane yz ##r## is the radius of the coil ##n## is the number of spiral by length of the solenoid. ##N## is the number of turns of the coil ##w## is the angular velocity that...

I don't understand why they said that the induced current flow is opposite to each other when it clearly states direction is to the right for both? https://www.physicsforums.com/attachments/285900

Hi, I was practicing some problems on the magnetic field and the electromotive force, when I got stuck on these two exercises. Could you help me figure out how to proceed? In the first problem, I tried to find the magnetic field flux by multiplying the induced current for ∆t and R. Should I now...

Why is ##E = \int (\vec v \times \vec B) \cdot d \vec l##? This seems to be a general formula, and I would like to know its proof. Thanks for all the help.

I used the voltage of the power supply and resistance to solve for the current in the larger circuit (20V/5ohms=4 amps). I am not sure if the equation listed above is the correct one I should be using, but I tried it using the following numbers. For omega, I used 2*pi*frequency. N should...

We know in Lorentzian signature spacetime, in the case of timelike or spacelike hypersurfaces ##\Sigma## with \begin{align} n^\alpha n_\alpha=\epsilon=\pm1 \end{align} where ##\epsilon=1## for timelike and ##-1## for spacelike. We can define a tensor ## h_{\alpha\beta}## on ##\Sigma## by...

I used the equation below and the attachment to rationalize. https://www.physicsforums.com/attachments/282163

As we know that the magnetic induction causes an electric current in a wire and Faraday has formulated his Electromotive equation ##\epsilon=-\frac{d\Phi}{dt}##. And then Maxwell-Faraday's equation is: ##\nabla \times E=-\frac{\partial B}{\partial t}##, until now this was just an introduction...