# lenz's law

1. ### I Question regarding Lenz's law

I've attached an illustration of my set up.
2. ### Lenz's Law for a rotating PM motor rotor spinning in a thin CU tube

The motor is required to operate at its resonance frequency and I am looking to add a thin-walled (0.010") copper tube inside the stator bore to add some damping. The current motor air-gap is 0.015". If I install a copper tube in the stator bore bonded to the stator and leave a 0.005" air-gap...
3. ### Find induced current, magnetic force, work in inclined plane

Homework Statement A conducting bar slides down without friction on a pair of conducting rails separated by distance d. Connected to resistor R and there magnetic field B directed upward, perpendicular to the ground over the entire region through which the bar moves. 1) find the current 2)...
4. ### What is the direction of the current in the given image?

Homework Statement In the picture 20.40, what is the direction of the current induced in the resistor at the instant the switch is closed.[/B] Homework Equations Right hand rules- Point thumb in direction of current and your fingers will curl in direction of magnetic field. Lenz's law. The...
5. ### Speed of a Magnet Falling through a Conducting Wire

Homework Statement A small but very powerful bar magnet falls from rest under gravity through the center of a horizontal ring of conducting wire, as shown in the figure below (on the left). The speed-versus-time graph, in arbitrary units, of the magnet will correspond most closely to which of...
6. B

### Magnetic Flux Questions from Japanese University Exam Papers

Hello everyone, This is my first post here Firstly, I'd like to start by saying that it's my best intention to follow the rules on this forum. Therefore, if I've posted this in the wrong section please forgive me, I will try and learn the ropes quickly. One of my students has given me some...
7. ### What force does the current carrying coil feel?

Homework Statement What direction does the force that the current carrying coil feel point to when a magnetic field is turned on? A magnetic field is turned on and points from bottom to top and passes through a current carrying coil that has current passing through it CCW. Here is a diagram...
8. ### I Ballistic Lenz's Law

If a magnet was going fast enough as it approached/entered a copper tube, could the current induced in the tube via Lenz's Law be high enough to melt or even vaporize the tube?
9. ### B Textbook picture: Is direction of this eddy current wrong?

Hi. This is from a high school textbook, in a chapter about eddy currents and Lenz's law. In a), a magnetic field is turned on, in b) it's turned off, which both induces a current in a suspended aluminium ring: I think the direction of the current is wrong in both pictures. Any opinions?
10. ### I Lenz's Law

I'm working on induction at the moment, and the math makes sense, but Lenz's Law is giving me trouble. Does anyone have an easier way (relatively) of remembering the directions of emf? Any advice is appreciated.
11. ### I Lenz's Law in action with different length magnets

Hi, I was doing an experiment with Neodymium magnets and a long copper pipe (3cm internal diameter) to see Lenz's Law in action. At first I used a long bar magnet (about 15cm long) and there was little resistance to the magnet falling through the pipe. It was only slightly slower than a...
12. ### I Faraday's and Lenz law - Experiment with AC coil and Cu ring

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...
13. ### I How are Lenz's law and Faraday's law connected?

I want to know the angle of view from which Lenz's law and Faraday's law can be seen methodically.
14. ### A motor design to defy Lenz' law?

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 feilds...
15. ### Electromagnetic Induction

Homework Statement Homework Equations Not really? I just used the right hand rule and Lenz's law The Attempt at a Solution By the right hand rule, outside of loop 1, the magnetic field is out of the page. However, increasing resistance means that field is weakening. We know by Lenz's law...
16. ### Motional EMF: Minus sign

I'm trying to understand how electric generators work on a very basic level. I understand the heart of this is the application of the Lorentz force on a conductor moving at a velocity $v$ in the presence of a magnetic field $B$. I also understand how it can be shown that the emf is equal to...
17. ### Lenz' Law question

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...
18. ### Are induced currents created by motion or change in flux?

The book I am working through is beginning to dive into induced currents and Lenz's Law. When a conductor is moving perpendicular to a magnetic field, the charge carriers inside will experience a magnetic force; This causes the charges to move. Eventually, the electric field from the charge...
19. ### Force on a Magnet in Lenz's Law

Homework Statement As the bar magnet (see attached diagram) leaves the loop of wire, it experiences a force opposing its exit. I understand why, according to Lenz's law, a force would oppose the bar magnet's exit. I don't understand, however, what causes the force. In this case, the force is...
20. ### Back emf in a single loop of wire?

I have been thinking about coils of wire carrying alternatingcurrent. From what I understand, a back emf is induced in the coil because there is a changing magnetic field around each individual loop of wire, and therefore there is a changing flux through each loop because the changing field...
21. ### Ampere's law question

First, some background. In Faraday's law the reluctance/resistance by "mother nature" to changing the magnetic flux is explicitly recognized by the "-" sign (commonly referred to as Lenz's law), i.e. if the time rate of change of the magnetic flux is positive, an emf is induced so as to oppose...
22. ### Small magnets and Lenz's Law

In all demonstrations of Lenz's Law that I've seen about the falling magnet, the diameter of the magnet is roughly the same size as that of the tube. Would there be any difference if the magnet was significantly smaller?
23. ### Lenz's Law and multiple tubes

Obviously if a magnet falls down a conducting tube, it induces a current in the tube. But what if you surrounded the tube with other identical tubes in parallel with the first one so that they're touching, and then wrapped wire around those other tubes? Would the current induced in the wrapped...
24. ### Voltage drop across ideal solenoidal inductor

First by ideal I mean zero resistance. I tried to verify Faraday's law in simple LCR circuit but ran into some conflicting results. Though the description below will be a little verbose, the configuration for this problem is extremely simple: assume that I put a solenoid...
25. ### E-induced lines

In electrostatics, ∇ × E = 0 so E that is a conservative field and there must be sources of E from which E flows. We know that this sources are the electrical charges given by Gauss' Law. But when B changes in time, ∇ × E = - ∂ B / ∂t. Now the Gauss' Law no longer applies and if there are not...
26. ### How does this hoverboard work?

https://www.kickstarter.com/projects/142464853/hendo-hoverboards-worlds-first-real-hoverboard I see that it says it's based on Lenz's law, which says that the induced currents will generate a field that opposes the change in the field. So, I figure they have some kind of oscillating magnetic...