Examining the ability of citric acid to conduct voltage is a classic science experiment for children. Gather a lemon, copper nail, zinc nail and 12-inch length of plastic coated wire. Cut the wire in half and strip 1 inch of insulation from both ends of each wire. Wrap the end of one wire around the copper nail head and the end of the other piece of wire around the zinc nail head. Insert the nail tips into the lemon, approximately 2 inches apart. Instruct students to touch the unattached ends of the wires to their tongues and describe what happens. Repeat the experiment using different fruits to determine which varieties conduct voltage.
A current of 1.5 volts is a safe amount for classroom use, and elementary teachers can conduct simple experiment to demonstrate current flow to children. Provide students with a 1.5V flashlight battery, screwdriver, two 10-inch lengths of 22 gauge single-strand insulated copper wire and a flashlight bulb in its socket with its screws. Inform students they have all the necessary materials to illuminate the light bulb and encourage them to assemble the pieces correctly to create a working circuit. When the flashlight bulb is tightly screwed in, and each length of wire is connected to one battery node and one screw in the flashlight socket, the bulb should illuminate. If it does not, tighten the screws onto the wire ends with the screwdriver and check the bulb to make sure it is not faulty.
Students can demonstrate the relationship between electric and magnetic fields by creating an electromagnet for a class assignment or science fair project. A 1.5V dry cell battery, 1 meter of 22-gauge insulated wire with an inch stripped on each end, a 10-centimeter nail and several paper clips are the only materials required to complete the experiments. Instruct students to hold the nail in one hand and coil the wire around the nail shaft 10 times with the other hand. When students hold the nail near the paper clips on a table, they will observe that nothing happens. Attach one end of the wire to a battery terminal and bring the nail near the paper clips again. Connect the other end of the wire to the second battery terminal and hold the nail near the paper clips. Disconnect one end and hold the nail above the table. This experiment shows observers that electrical power generates a magnetic field around the nail and the nail will hold that magnetic charge briefly after disconnection, but the paper clips will drop as the nail loses its magnetism.
To help students create a working circuit, the teacher should show them how to categorize items as conductors or nonconductors of electricity with a battery test. You'll need the materials you used in the previous flashlight bulb experiment, plus a third piece of copper wire. Connect a piece of wire between the bulb in the socket and the 1.5V dry cell battery. Attach a second piece of wire to the other battery node and a third wire to the other side of the flashlight socket, but do not join the second and third wires. Ask students to supply items in the classroom such as pencils, paper clips, thumbtacks, coins and glue sticks. Discuss which items the class agrees will or will not conduct electricity. Test the hypothesis by connecting the loose wire ends to each classroom object. The electric conductors will illuminate the flashlight bulb, while nothing will happen when the nonconductors are attached. Identify common physical properties of conductors and nonconductors; for example, wood and plastic objects do not conduct electricity.