Eb-10 Lenz’s Law (2 Coils on a Pipe)


To demonstrate the induced EMF when there is relative motion between a conductor and a magnetic field.


  • Plastic Pipe with coils attached to the outside. Coils have LED’s attached
  • Neodymium Boron Magnet

Lenzs Law 2 Coils on a Pipe

2 LED Coils on a Pipe plus Magnets


The apparatus consists of a clear plastic pipe which has two coils placed approximately 50cm apart. The coils are each directly connected to an LED.

A Neodymium Boron magnet is dropped down the plastic pipe. As it passes the coils, it induces a current in the coils, which causes the LED’s attached to the coils to light up. The demonstration may be used in conjunction with the Eddy current pipe demonstration to illustrate that the falling magnet induces eddy currents that oppose the fall of the magnet.

Safety Notes

Lenz's Law (2 Coils on a Pipe) SOP-21