A bar magnet inside a copper coil (i.e., a solenoid) is connected to a hand cranked electricity generator. The magnet is hung from a spring at a height where the magnet is just barely inside the copper coil. When the hand crank generator is turned, it creates an electric current through the copper coil. This electric current runs through each coil and creates a small magnetic field pointing either up toward the ceiling or down toward the ground, depending on the direction the hand crank is turned. These individual magnetic fields sum to create a larger magnetic field that then applies a force on the bar magnet hanging from the spring. As the magnetic force is applied, the magnet will be pushed upward or downward depending on the hand crank direction. Likewise, once the bar magnet starts oscillating through the copper coil, it will create a current in the coil which then applies a force on the hand crank electricity generator, though this force will be much weaker.