With a few readily available household items anyone can create this experiment in 5 - 10 minutes, demonstrating magneto hydro dynamics. Basically, when electricity moves through a conductive fluid in a magnetic field, a force, called the Lorentz Force, is imparted on the fluid, causing it to move.
More can be read about it here: en.wikipedia.org/wiki/Lorentz_force
Step 1: Household Materials
1 small circular magnet (can be purchased cheap at any hardware store)
1 small white cap
1 9 volt battery
Step 2: Mix a Dash of Salt Into Some Water
Water is not a very good conductor of electricity so we'll need to add some salt to make it conductive.
Fill up the white cap with water and mix in a pinch of salt.
Step 3: Lightly Sprinkle Some Pepper Onto the Saltwater Mix
The pepper is used for visualizing the circular motion of the water.
Step 4: Place the Cap With the Saltwater/pepper Mixture on the Magnet
The water will flow clockwise or counterclockwise depending on the orientation of the magnet. Feel free to flip the magnet and watch the water switch directions.
Step 5: Attach a Small Nail to the Battery
The 9 volt battery was perfect for holding in one of the nails. You can tape or hold with your fingers the other nail against the other battery connector (terminal).
Step 6: Insert One Nail Into Center of Cap and the Other on the Outside Rim
You will see the pepper start flowing around the center nail. Basically when electricity flows thru a conductive fluid in a magnetic field, a force is imparted on the fluid making it spin.