Force on a Conductor in a Magnetic Field (Laplace Law)

To demonstrate the electromagnetism. A pair of powerful magnets in U shape holder. A pair of brass rail with 4 mm socket is used for demonstration. A brass axle with two plastic discs is free to roll along the rails and complete the circuit between rails. As the axle placed on the rails near the poles of magnets and power supplied to the rails, the axle repelled and rolls away from the center of magnetic field along the rails.