Ahh, Physics, you never cease to astound me. Today’s awesome science demo is brought to you by Lenz’s Law. Heinrich Emil Lenz was a German physicist that formulated a law of electromagnetic induction back in 1833. The most stripped down explanation of the law is that when a current is induced in a conductor, a magnetic field is generated that opposes the action that produces the current. Check out a demonstration of this in action in the YouTube video below.
Read more : http://www.iflscience.com/physics/what-happens-when-you-drop-magnet-through-copper-tube#e3s70axF0bJrJkae.99