# All Questions

83 questions
34 views

### Is it possible to use Ampere's law to calculate vector B around short straight line conductor?

Maybe this question sounds easy, but I would really be grateful if someone could give me an explanation if it's true or not. I'm not sure if I understand it good enough.
64 views

### Can $F=qvB$ be applied to a solenoid and a parallel moving magnet?

If you take a scenario like this, Charge gathers at either end, and if you could somehow form a complete circuit without there being a canceling effect, there would be a current flowing. This makes ...
96 views

### Is there is any way to prove the Faraday's law of induction?

I want to know if there is any way to prove the Faraday's law or is it just an experimental observed phenomena? More specifically, is there any reason why the proportionality constant is 1? How did ...
151 views

### Magnetic field inside conductor and linearity of eddy currents

Eddy currents are currents that are generated in a conductor to produce magnetic fields that oppose the magnetic field originally produced by current flowing in the conductor. The figure below (from ...
66 views

### Will a pulsating electron beam passing through a copper pipe induce eddy currents within the copper pipe?

If a pulsating electron beam is beamed down the center of a copper pipe, so as to not make any physical contact with the pipe, the beam should create a pulsating magnetic field that will not change in ...
40 views

### Effect of greater coils on induced current in a solenoid

Simple case:- A bar magnet is inserted into a solenoid with 'n' turns at velocity 'v'. The current is measured using an ammeter that is part of the complete circuit of the solenoid. My question is ...
145 views

### Do magnets attract magnetic materials by inducing magnetism in them?

Here are 2 concise excerpts from a book I have been reading:- 1.A permanent magnet produces its own magnetic field. An induced magnet is a material that becomes a magnet when it is placed in a ...
54 views

### Finding induced magnetic field strength given current.

I'm working on a project involving a Tesla Coil, and I was hoping to figure out how strong an induced magnetic field would be with an input voltage of X. Is there an equation to help solve this? I'm ...
57 views

### What would happen if i move a rectangle shaped conductor in a magnetic field?

I know that in situation II there will be a induction current; and there will be no induction current because of the constant magnetic flux in situation I; but when we move a linear conductor in a ...
75 views

### Why is the change in flux in Faradays law proportional to the area enclosed by the wire rather than the wire area perpendicular to the magnetic field?

When deriving Faraday's law in high school physics the change of the area enclosed by the loop of wire is said to be proportional to the change of magnetic flux in Faraday's law. Intuitively, it makes ...
807 views

### Does a wire/rod moving through a magnetic field have any change in flux?

I know that if we move a rectangular wire from no magnetic field to through a magnetic field, there would be an induced voltage because there is change in flux (b∆x). However, if we moved a wire/rod ...
57 views

### If an inductor has current flowing in only one direction, does the magnetic field still vary directions?

My understanding is that in a standard AC inductor the magnetic field in the core changes direction as the current through the primary coil alternates. What if the current through the primary coil was ...
510 views

### Straight wire with constant electric current and square loop in the gravity field

I was trying to solve this exercise but I found some difficulties in the proposed solution... The text is: A square loop of wire (side $l$, mass $m$, resistance $R$) lies on the $xz$ plane, below a ...
278 views

### Finding the induced current in a loop and force acting on the conductor

The conductor has a velocity to the right and is part of a closed loop (see the picture). Find the direction of the induced current and the direction of the magnetic force on the conductor There must ...
371 views

### Induced Current and Force

I am preparing for an exam in electricity and magnetism, and I came across this problem in my book with a solution that confuses me: A conducting loop of wire is initially around a magnet as shown ...
920 views

### Current induced in loop moving out of magnetic field : contradiction using Fleming's right hand rule

In the picture shown magnetic field exists into the plane (denotes by the X) and the loop (iii) is moving out of the region of the magnetic field. According to Lenz's law, the induced current will ...
547 views

### Voltage generated in moving wire

hyperphysics: When a conductor moves through a magnetic field, there will be a generated motional emf. This is one example of Faraday's Law and it arises from the magnetic force. I don't ...
126 views

### Induction heating

An induction cooktop has a high frequency power source that is applied to a coil. I was wondering if you could take the high frequency electronics on a cooktop and instead of a coil take a 30 or 90 ...
50 views

### Current Induction Explanation

Using $$F_\text{magnetic} = (BIL)_\text{wire} = (BQv)_\text{particle}$$ we can say $F\propto v$ as $B$ and $Q$ are presumably constant. Is the magnetic force proportional the radius, or distance, ...
392 views

### Resulting magnetic flux in the core of a transformer

In a transformer, let's say we have: $I_1, I_2$ - currents through the primary and secondary winding $V_1, V_2$ - voltages $N_1, N_2$ - number of turns $F_1, F_2$ - magnetic fluxes through core, ...
574 views

### Induced emf in ring in magnetic field

A metal ring is placed in a magnetic field. The ring has a gap in it though. As it falls through the magnetic field, is it true that it still experiences an induced emf and eddy currents but not a ...
15k views

### If you are vacuuming your carpet and you wrap the cord around your body do you become a magnet?

If you wrap an active electric cord around your body, do you become an electromagnet?
74 views

### What are current density in these experiments with neodymium magnet levitation?

Here is the video: https://www.youtube.com/watch?v=keMpUaoA3Tg Experimenter throws neodymium magnet into copper tube. Apparently, it induces currents in the copper, which create magnetic fields, ...
38 views

### Conductor in motion in a magnetic field

I have the following exercise: there is a square conductor of a given side L and resistance R. The conductor is surrounded by a magnetic field B (90° with the y-axis) and it depends from z: B(z) = K*z,...
916 views

### Spinning a bar magnet above a disc

I'm preparing for a physics exam and this scenario was in one of the past papers: If I have a horizontal bar magnet connected to a motor, and directly underneath there is a horizontal copper disc ...
4k views

### Why does induced current depend on the area of a loop of wire?

My year 12 physics textbook teaches the concept of electromagnetic induction in a rather unintuitive way. Perhaps it is not being thorough. Perhaps I am not being thorough in reading it. Here is my ...
325 views

### Use of tungsten as an insulator in an induction heater

One problem in induction heating is that energy is lost because the object being heated radiates energy, that energy then heats the coils (which are water cooled) and the coils suck away the energy. ...
932 views

### How to calculate the energy transfer between working coil and working piece and dissipated energy of working piece in induction heating?

For who don't know how does induction heating work, a short description can be found here. However, my question is about physics. Assume I have a coil inductor calculated carefully 50 uH as below: ...
119 views

### What would happen if a magnet was pushed towards a copper tube in space?

So the question was inspired by one of curious comments on youtube. What exactly would happen if you pushed a strong neodymium magnet towards the copper tube (aiming for the opening in an effort to ...
54 views

### Magnetic Forces and Junkyard Magnets: What's Going On? [duplicate]

In my electromagnetic theory class, I learned that magnetic forces do no work. This is easy to see when observing a cyclotron; the speed never changes, so the kinetic energy never changes and ...
991 views

### Motion in a time-dependent uniform magnetic field

Suppose you have an infinite solenoid generating an uniform magnetic field inside. The field is oriented along the solenoid axis : unit vector $\vec{\bf n}$. The field intensity varies linearly with ...
2k 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?
7k views

### How to find the direction of an eddy current?

Suppose there is a magnetic field going from left to right. Suppose a thin sheet of metal conductor (e.g. a 1m*1m square) is dropped through the magnetic field such that the plane of the conductor is ...
169 views

### Can magnets induce magnetism stronger then their own magnetism?

This might sound foolish but bear with me for the explanation. I came across a weird magnetic behaviour playing with coins on a mac. There are magnets in mac, two on the top corners of the screen and ...
852 views

### Why in electrostatics is $dV=-E.dr$ but in electromagnetic induction, $EMF=+E.dS$?

In electrostatics we learned that $$dV=-E.dr$$. I understood the derivation which was used to derive this. Now when I have come to Electromagnetic Induction,I see that when there is a time varying ...
69 views

### Does resonant inductive coupling work in the presence of a strong magnetic field?

Does resonant inductive coupling work in the presence of a strong magnetic field? I am unsure because resonant inductive coupling uses magnetic fields to transmit power wirelessly and a strong ...
109 views

### Induction equation in a rotating frame

In his book, Tom Cravens refers to the induction equation (perfectly conducting limit) in a rotating frame, the Sun. See link below: https://books.google.com/books?id=xw50iZep-McC&pg=PA222&...
312 views

### What happens if I have a square conducting wire being permeated by a magnetic field and the field suddenly disappears?

Suppose there is a square conducting wire in a magnetic field. The two vertical branches will have the same emf, and the two horizontal branches will have 0 emf, resulting in a net emf of zero and ...
2k views

### Zero current induced in a loop

Consider the following two cases, Case 1 – A coil moving through a constant magnetic field Case 2 – A conductor moving through a constant magnetic field Now, in Case 1 (a coil moving through a ...
798 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 ...
45 views

### Does the wireless energy tranmission affect compass

Wireless energy using magnetic inductive coupling. So magnetic field will be affect around device. We use it to charge mobile device so I wonder if it will affect compass in our device
91 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 ...
991 views

### Induced magnetic field produces electric field and vice versa forever!

So here are the two of Maxwell's laws that I am interested in: So we have the simple circuit (from google): So, before the system goes into steady-state we know that charge slowly accumulates on the ...
32 views

### Average induction voltage

I've got a basic question on the method of computing the average induction voltage. Here is the task: A conductor loop with the area $A_1 = 50\text{cm}^2$ in a magnetic field with the flux density of ...
534 views

### Pulling a bar through a magnetic field

This is a question on magnetic flux and induced voltage. I believe that this problem's answer key is incorrect, and I want to determine whether my opinion is sound. I also want to explore one sub-...
814 views

### Where is the energy stored in an inductor?

In an inductor, Most text books say that the $(1/2)Li^2$ is stored in the magnetic field. But is there another way to explain this? In a capacitor I understand that all the energy that the battery ...
2k views

### Ed Leedskalnin's “Perpetual Motion Holder” (PMH)

Edward Leedskalnin (Coral Castle) describes a perpetual motion holder in his writings. I've built one and pretty much know how it works (I think). It is NOT a perpetual motion device by any means, ...
4k views

### Derivation of Faraday's law using Lorentz force?

For a stationary loop of wire with a time varying magnetic field $\vec{B}(t)$ through it. Is it possible to derive Faraday's law, using only the Lorentz force \vec{F}=q \vec v\times \vec B \tag {1}\$...