Wind 5 feet of insulated copper wire around a drinking straw to make a 3-inch-long solenoid. Trim the straw ends so just the ends stick out of the solenoid. Hold the solenoid in the horizontal position and insert a needle partway in the straw. Strip an inch off the ends of the wound wire and connect them to a 6-volt battery. The needle will be sucked through the straw because of the strong magnetic field created by the electric current flowing through the tight coils of wire.
Take three meters of 22-gauge insulated stranded copper wire and tightly wrap it around a 15-inch-long nail in one direction. The direction is important to create a stronger magnetic field as the direction of a magnetic field depends on the direction of electric current. Use a pair of wire strippers on the ends of the unwound wire and strip an inch of insulation before connecting them to the two terminals of a D-cell battery. You can hook the ends of the wire to the positive or negative terminal as reversing the battery connection will only influence the magnetic polarity. Bring some paper clips near the point of the nail and see them bind to the iron core. Disconnect the battery to demonstrate that the iron core loses its magnetism. This experiment shows that electric current that passes through a wire magnetizes the iron core. Students learn that electromagnets run on electricity and only flowing electricity makes electromagnets magnetic. Explain to the students the significance of current on an electromagnet in the ringing of a doorbell; pressing the button enables current flow that magnetizes the electromagnet; the electromagnet attracts a small hammer that is pulled back by a spring to strike the bell when the circuit breaks.
This experiment tests the result of running an electric charge through a magnet. Put a stainless steel cow magnet into a box of paper clips and pull it out to count the number of paper clips stuck to the magnet. Repeat the process three times and find the average. Wrap the same magnet with 10 turns of copper wire (use a yard of wire) and strip off the insulation from the wire ends before connecting it to the poles of a 9-volt battery to create an electromagnet. Place this magnet in the box of paper clips and find the number of clips the electromagnet attracts. Repeat the process three times to find the average number of clips stuck to the magnet. Disconnect the battery. Unwind the copper wire from the electromagnet and place it in the box of paper clips. Repeat the process three times and find the average number of clips stuck to the magnet in the absence of electricity. You will find that the magnetic property is highest in the presence of electric current and lowest in the magnet that was not subject to electric current. The number of clips stuck to the magnet connected to the battery will be higher than the number counted in the absence of current after disconnecting the battery. This experiment concludes that running electric current through a magnet increases its magnetic power.
You need three permanent bar magnets and a toy car to conduct the propulsion experiment. Tape one magnet to a small toy car so the magnet’s north pole is at the back of the car and south pole is at the front. Place the south pole of the second magnet behind the car. When you take it near the car, you will find that the car moves forward. This occurs because the south pole of the second magnet repels the north pole of the taped magnet to propel the car forward. Have another student place the north pole of third magnet near the south pole of the taped magnet. You will find that the car is pulled faster with one magnet propelling from behind and another magnet pulling from ahead. This occurs because the taped magnet is repelled by the magnet that is behind and is attracted by the one in front. This experiment simulates the movement of a magnetically levitated train in which the electromagnets produces magnetic force that pushes the train from behind and pulls it from the front. The electromagnets in the track change poles by changing the direction of electric current.