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- Homework Statement
- Finding the braking torque applied on a moving disk as a result of the Eddy Currents

- Homework Equations
- $$F = \sigma v V B^2$$

**Homework Statement:**Finding the braking torque applied on a moving disk as a result of the Eddy Currents

**Homework Equations:**$$F = \sigma v V B^2$$

So right,

Basically my problem is how to find the torque exerted by an eddy current braking setup.

My setup consists of a disk rotating on an axle and five magnets on a frame next to the disk. When the magnets are directly over the disk, the eddy current force produced retards and stops the disk. I'm trying to quantify this force based off of the magnetic field strength and velocity or frequency of the disk.

Where I started off was this PF thread where they concluded the Eddy Current Braking force as $$ J\times B$$ Which when ##J## is substituted as ##\sigma(v \times B)## simplifies to $$F = \sigma v V B^2$$ However, the problems I had with this, is that firstly it didn't match my data, when I empirically calculated torque through rate of change of angular momentum. Also, on the last few messages on that thread, there is a mention of integration over r, which I'm not sure what that means.

I have seen this paper by Smythe on several sites, as well as others by Wiederick and others, trying to make an analytical model of eddy-current braking. However, unfortunately the maths used looks quite confusing for me. So I'd appreciate it if someone over here could help me out with this problem..