Lenz Definition and 49 Threads

This the images of the figure. I am confused on why is the magnetic field for the top wired is out and the bottom is in. Is that the general rule?? Moreover what if the wired is point to the left instead of right is the magnetic field still out of the page.

In this question I can't understand how the loop is opposing the change in flux, I can solve it by simply imagining a bar magnetic with south pole pointing outwards placed inside the plane of image but how do I know that it is the same case as that of bar magnet? What if their is a case in...

Hello, I am new and I have a question about the lenz law. How I am suppose to find DA/dt and o in this problem? A= 9 but D(9)/dt is equal to 0 ? And I don't really know what is the angle o means in this formula. If I found the voltage i can find the current with I= eps/Req .

Consider the following, a magnet and a charge is attached to a platform, which is constrained to move only up and down direction. Now, if magnet is moved towards charge, due to changing magnetic field, an electric field will be created. This electric field will impart force on charge. since the...

Above is an example figure. 2. When a ring in a changing magnetic field is not complete (i.e. open circuit with a small gap), how to analyze the emf of the ring? According to the general form of Faraday's law, ## \oint \vec{E} \cdot d \vec{s} = -\frac{d \Phi}{dt} ##, I deduce that although it...

I have been studying electromagnetic induction and have looked at the laws of Faraday and Lenz. Faraday's law makes perfect sense to me, but I can't seem to grasp Lenz's law. I have read about it and watched many yt videos, and the idea seems simple. But actually using it to predict e.g. the...

Homework Statement A straight wire of length 0.20m moves at a steady speed of 3.0m/s at right angles to a magnetic filed of flux density 0.10T. Use Faraday's law to determine the e.m.f. induced across the ends of a wire. Homework Equations E= Nd Φ/dt but N=1 so E= dΦ/dt The Attempt at a...

Homework Statement You have a circular coil, and two metal plates a and b. The north pole of a bar magnet is moved away from the coil at a constant velocity(assume the bar magnet and the coil lies along the x axis). On which plate will the excess positive charge appear? Homework EquationsThe...

Homework Statement Assume a uniform hollow cylindrical copper tube with the following parameters: Inner radius = R0 Outer Radius = R1 Length = L1 (Length > Outer Radius) Mass = M1 Now assume a cylindrical permanent magnet with the parameters: Length = L0 (L0 < L1) Mass = M0 Magnetic...

Hi. Superconductors can be made hover above or even below magnets. As far as I know, this can be interpreted as an extreme form of Lenz's law: Eddy currents on the surface of the superconductor create an opposing force that is able to cancel gravity since the currents aren't affected by...

Hi. According to Lenz's law, a conducting ring responds to an increasing external magnetic field with a repelling field and to a decreasing external magnetic field with an attracting one. Thomson's experiment uses an AC coil, so its field strength changes between increasing and decreasing a...

Why is it that the induced emf opposes the change in magnetic flux? Is it to follow the law of conservation of energy?

Hi, can someone explain me the next experiment: If I have an AC coil on iron stick, and if I put Cu ring on that stick concentric with AC coil, when I turn coil power supply, the ring will levitate on some height. My question is: Powered AC coil produces an AC magnetic field. If I put a...

1. The two rotors (purple, green) are electricaly isolated but mechanically fit to rotate along same axis 2. The motor action on the left side rotor will move the armature set, this will produce currents in right side rotor that will pass via a variable load. 3. do you see the magnetic fields...

Homework Statement I have attached a picture that details the problem. This is my practice test and I have no clue what I am doing wrong. Essentially a loop of wire is moving in constant velocity into a magnetic field. The magnetic field lines are pointing into the page. The problem is...

Homework Statement There is a magnetic field directed inside/ towards the screen. There is also a single rectangular coil parallel to the screen where one of the sides are movable. The magnetc field increases, what happens to this movable side of the coil. This is my description of the...

I understand why slowing the current, causing a decrease in the flux, momentarily increases the current (stabilizing). I can use the right hand rule and Lenz's law to picture what is happening in that case. But why does increasing the current add resistance? The induced magnetic field is...

I had the idea of making an hourglass timepiece employing lenz's law using a magnet and copper tube (or copper bars for visibility). Any idea how accurate my hourglass will be? I know Lenz's law is effected by temperature (not sure by how much). If I drop a small magnet drop through a small...

I was reading through my College Physics text, and it talked about how NASA once swung a 20km long conductor through the Earth's magnetic field and setup a 3500V potential difference along the wire. I understand that there's no conventional current in that wire, it's not a circuit. But for a...

Homework Statement A long, straight wire lies on a table and carries a current I. As the drawing shows, a small circular loop of wire is pushed across the top of the table from position 1 to position 2. Determine the direction of the induced current, clockwise or counterclockwise, as the loop...

Hello Physics forum, I have come here seeking for some experienced help about a doubt that to some extent is not letting me advance on my studies of electromagnetism. Basically is about the magnetic (B) field, and more specifically, about the force at each point of the vector field (The lorentz...

In the attached figure, a de-energizing RL circuit is drawn (left switch is opened while right switch is closed). In the drawing the voltage induced in the inductor is put to be negative so that the math works out. However, that would be against Lenz's law, wouldn't it? The inductor should be...

Homework Statement For each of the following scenarios, predict the direction of the induced current ( c-to-d; d-to-c; NO INDUCED CURRENT) in the second set of coils, N2. 1. The current, I1, direction ‘a-to-b’, is increasing rapidly. The coils remain stationary. 2. The...

So say you have a square loop of wire which has a current of some positive value going clockwise and it enters a magnetic field going into the board. Now since lenz law states that the induced emf will make a current going counterclockwise (to oppose changing mag flux) then what is the new...

Hi All! This is my first question/post here, so I will try to make it work! Homework Statement Ok, so the question is simple-ish. Homework Equations Faradays Law (ε=-NΔΘ/ΔT) The Attempt at a Solution Now, I understand the concept that as the magnet is falling towards the coil, the coil...

The purpose of the lab was to measure, and also calculate, the induced current in a disconnected coil, due to a second coil connected to a power supply. Involved magnetic fields and electric fields (I think. For the purposes of this lab, the magnetic permittivity is 1.26*10-6, the number...

Important: Imagine that there is a wire connecting the two magnetic poles, (+,-) so there is an induced current and not only an ems. Homework Statement Hello there! I'm wondering if I can use both of these methods to calculate the direction of the current. The first one is Lenz...

Homework Statement \mathbf{A} = \frac{1}{2}\left(\hbar\mathbf{L} \times \mathbf{p} \right) - \frac{1}{2}\left(\mathbf{p} \times \hbar\mathbf{L} \right) + Ze^2m \frac{\mathbf{r}}{r} Derive \mathbf{A}^2 = \left(\mathbf{p}^2 - 2m\frac{Ze^2}{r} \right)\left(\hbar^2 \mathbf{L^2} +...

For the classic Lenz law demonstration using a neo. magnet dropped down a copper pipe, is the magnetic force generated correlated to the thickness of the copper pipe? Ergo, will the magnet go slower down a thick copper pipe vs. a standard size plumber pipe?

After watching a fascinating youtube video demonstrating the Lenz Effect using a 1.5T MRI machine and an aluminum block, I was wondering if it would stop a bullet fired along the axis of the machine. If so, would there be any defensive military application?

Homework Statement If we drop a bar magnet down a copper tube, it will travel down very slowly. If we now cut vertical slits in the copper tube, will the magnet travel down faster or slower as compared to the original problem? Homework Equations \int \vec E \cdot d \vec l = -\frac{d...

Hi, Can somebody answer this question? The induced magnetic field of the secondary coil opposes the magnetic field of the primary. Therefore there is a lower magnetic field on the primary - lower impedance and a lower voltage drop. This results in an increased primary current which will...

Homework Statement Figure shows two coils placed close to each other . When the key is pressed so that a current starts building up in one the coils (a) a current flows along CBA in the loop (b) a current flows along ABC in the loop (c) No current flows through the loop (d) An...

I am sick of searching and being confused more and more specially about lenz law... THere are many demonstrations and many law.. Can someone list atleast the most important one...

Lenz law problem wire and expanding loop Homework Statement The loop has current radius R the red bar moves at velocity V. The distance the wire is from the loop is d and the top of the loop is length l Find the induced emf and the direction of the current in the loop. Homework Equations...

Question about Lenz Law. When a magnet is moved towards a coil, it produces a current in the coil. The current flows in the coil in the direction which produces an "induced" magnetic field that pushes away the motion of the approaching magnet. Faster the magnet approaches, bigger the current...

Homework Statement A ring falls through a horseshoe magnet. Before reaching the magnet, is the current induced in the ring clockwise or counterclockwise? What about after the ring has passed through the magnet? The answers are clockwise before the ring passes through, and...

This started in the MIT professor's thread. But this part is concentrated on Faradays and Lenz law in constant magnetic flux loop and transformer that is very interesting and not quite relate to the MIT professor discussion. I want to bring this out and continue discussion about the Faraday's...

I am having trouble understanding how the right hand rule works with lenz's law. Please explain

hello to all, first post on this side of the web, maybe some of you folks can give me an opinion on something I've been running in my head ok, so this stemmed from thinking about how to overcome lenz law with gravity i thought of a magnet on the end of a lever, with a free standing...

in the following question i am given an infinite straight wire with a current changing according to i=2t, next to the wire is a conducting square with a side of a=5cm at t=0 the square is at a distance of b=5cm from the wire and the frame is moving away from the frame at v=2m/s, the frame has a...

Hello. I have problems with the Faraday and Lenz laws. Not problems with their definitions (they are OK), but with the usual assumptions and relation with conservation of energy: The definition of these two laws states: - Faraday law: The induced electromotive force or EMF in any closed...

A circuit contains a resistor and an uncharged capacitor. Pointing into the plane of the circuit is a uniform magnetic field (B). If the magnetic field increases in magnitude with time, which plate of the capacitor (top or bottom) becomes positively charged? I don't understand how the...

1. suppose a long solenoid is connected to a DC source and after a long time steady state has reached. And suddenly an iron rod is inserted in the solenoid along its axis. Obviously, self inductance of the solenoid will increase by some factor. [One can assume some resistance of of the solenoid...

So... am I understanding this right? Does Lenz's law suggest that the velocity of a magnet dropping (gravity) into a tube of coils will decelerate as it passes? By decelerate, I mean actually not accelerate as quickly as it would without coils around it. I am an idiot. Thanks in advance.

Basic question about Faraday's law? Hi guys, Ok I have a small problem with faraday's law. Taking the example of a north pole of a magnet coming close to a solenoid. My question is when the magnet is inside the coil and is stationary why is the induced current zero. Wouldn't the magnetic field...

Homework Statement Hi all. I can't seem to understand how to apply Lenz' law to a disc rotating in a magnetic field that is perpendicular to the discs plane (see first page on PDF): http://www.pa.uky.edu/~latimer/phy232s08/lectures/phy232l31_4.pdf I can see that using the right-hand...

What are the limitations of Lenz law? If there where none, you could just move a magnet through a coil and keep moving it away, thus creating the worlds most powerful magnet. This seems highly unlikely. When moving a magnet towards the coil, the external magnet field induces a current in the...

What was the original purpose of the Laplace Runge Lenz vector? I understand the components (comparing centrifugal force to gravitational force) and, more importantly, that if you multiply the LRL by the reciprical of the geocentric gravitational constant (or helio..., etc), you get a vector...