Eddy Currents and Magnetic Braking of a Pendulum Caused by Electromagnetic Induction
Why Physics Stack Exchange recommends it
Physics Stack Exchange answerers point people to it as a clear visual of how eddy currents arise in a moving conductor and how slotting or laminating the metal reduces them.
Recommended by 3 people across 3 different months, 2014 to 2021.
What it is
A short classroom-style demonstration of eddy currents and magnetic braking. A metal pendulum swings through a magnet gap and stops abruptly, while a grooved or comb-shaped pendulum, which limits eddy current flow, swings with little braking.
What people said
Recommends Brian Moths · 2014-05 · Physics Stack Exchange · on “Eddy currents and EMF?”
what do you mean by lamination? Is this [this video] something like what you are talking about? Just watch until two minutes or so.
Recommends Farcher · 2016-03 · Physics Stack Exchange · on “Eddy currents of a thin wire vs. a large plate?”
This video [this video] is the best illustration of the effect that I have seen because it introduces a third type of pendulum as well as the normal plane metal sheet (1) and the metal sheet in the form of a comb (2). It is a sheet with slots in it (3). [LINK] The plane metal sheet is your first example and the metal sheet in the form of a comb is your second example. The third sheet is the intermediate type. When a conductor passes at right angles to a magnetic field, an emf is induced - Faraday's Law. This happens in each of the sheets because of the force produced by the magnetic field on the moving mobile charge carriers in the metal plates. If there is a conducting path, currents are induced
Recommends fibonaccho · 2021-10 · Physics Stack Exchange · on “Is there a way to put a perpetual motion machine to work in space!”
Unfortunately for humanity, there is no way to get work out of a perpetual motion machine without dropping the "perpetual". The short answer is that the amount of energy in a closed system is conserved. Let's look at your system: it takes energy to increase the current in a copper wire. There are two sources of energy in your machine: the energy stored in the magnetic field and the energy of rotation. If the current increases, then, counterintuitive as it seems, the energy has to come from one of those places. Energy conservation is often useful in physics because it allows one to determine behavior of a system without having to get into messy details. However, you may be interested in these
Cites Farcher · 2017-09 · Physics Stack Exchange · on “How do Eddy currents follow conservation of energy?”
When eddy currents are induced in some way or other the work is done to change the magnetic flux or move a conductor though a magnetic field. That work done on the system finishes up as ohmic heating in the conductor. For example a conductor cutting magnetic field lines will have eddy currents produced within it. With no external sources of energy that conductor will slow down (lose kinetic energy) and that decrease in kinetic energy will be balanced by the conductor being heated. This conversion of kinetic energy into heat is illustrated in this video [this video] .
Cites streetcleaner · 2018-06 · Physics Stack Exchange · on “Will eddy current pendulum show deflection?”
Does the aluminium plate deflect due to its repulsion with the magnet? I thought it would deflect as in the case of 'jumping aluminium ring', however from the [this video] of this experiment, I cannot observe the deflection. Why?