Demo E-M Cannon
Connect solenoid to a source of alternating voltage.
http://wug.physics.uiuc.edu/courses/phys112/fall97/acts/lect16/act16b/sld001.htm
- The flux through the area ^ to axis of solenoid therefore changes in time.
- A conducting ring placed on top of the solenoid will have a current induced in it opposing this change.
- There will then be a force on the ring since it contains a current which is circulating in the presence of a magnetic field.