Metallic (non-ferromagnetic) and nonmetallic particles in solid waste may be separated as follows. The waste is allowed to slide down an incline over permanent magnets. The metallic particles slow down as compared to the nonmetallic ones and hence are separated. Discuss the role of eddy currents in the process.

When solid waste (metallic and non-metallic particles) allowed to slide over a permanent magnet, an emf will be induced in metallic particles. According to the Lenz's law, the direction of the induced current is such that it opposes the magnetic field that has induced it. So the induced emf in the metallic particles will oppose the downward notion along the inclined plane of the permanent magnet. And non-metallic particles are free from these effects. In this way, metallic particles slow down and get separated from the non-metallic particles.


1