Part 3/10:
He notes that the clearance between the magnet and the copper tube wall is only about 0.030 inches, which is critical in achieving optimal results. When the magnet is dropped through the tube, the time it takes to reach the bottom serves as a core measurement for understanding the effects of eddy currents — currents induced in the copper due to changing magnetic flux, which in turn create opposing magnetic fields according to Lenz's Law.