Homework help. Regarding Magnets, help!?A bar magnet falls slower when it falls through a copper pipe and faster if it falls through a plastic pipe. Why? I know it has to do with some type of current that is created around it that somehow slows this down. but i dont know how to explain it in proper terms. thanks in advance.
Magnet Through Copper Pipe
The moving magnet creates eddy currents in the copper that cause a counter force, slowing down the magnet. pedia: An eddy current (also known as Foucault current) is an electrical phenomenon discovered by French physicist Léon Foucault in 1851. It is caused when a conductor is exposed to a changing magnetic field due to relative motion of the field source and conductor; or due to variations of the field with time. This can cause a circulating flow of electrons, or a current, within the body of the conductor. These circulating eddies of current create induced magnetic fields that oppose the change of the original magnetic field due to Lenz's law, causing repulsive or drag forces between the conductor and the magnet. The stronger the applied magnetic field, or the greater the electrical conductivity of the conductor, or the faster the field that the conductor is exposed to changes, then the greater the currents that are developed and the greater the opposing field. The term eddy current comes from analogous currents seen in water when dragging an oar breadthwise: localised areas of turbulence known as eddies give rise to persistent vortices. Eddy currents, like all electric currents, generate heat as well as electromagnetic forces. The heat can be harnessed for induction heating. The electromagnetic forces can be used for levitation, creating movement, or to give a strong braking effect. In Eddy currents can often be minimised with thin plates, by lamination of conductors or other details of conductor shape. .
