By Robert Dumas
Updated Aug 30, 2022

Electrical conductivity is a material’s ability to carry an electric current. While metals are renowned conductors, many everyday objects can demonstrate this property in a classroom or science‑fair setting. The following experiments use common household items, crafts supplies, and inexpensive electronics to reveal how materials, solutions, and even soil conduct electricity.

Best Electrical Conductors

Objective: Determine which of the following materials conducts electricity best: metal, air, water, or plastic.

1. Place a 6‑by‑12‑inch board on a flat surface.
2. Position a battery and a flashlight bulb on opposite ends of the board.
3. Connect the battery’s positive terminal to one bulb terminal with a wire.
4. Attach a second wire to the battery’s negative terminal; leave the other end free.
5. Attach a third wire to the bulb’s unused terminal; leave the other end free.
6. Glue a small plastic cup, a metal paper clip, and a plastic straw to the board’s center. Fill the cup with water.
7. Touch the free ends of the two wires (one from the bulb, one from the battery) to each object in turn and observe whether the bulb lights.
8. Test air conductivity by holding the two free wires as close together as possible without touching.
9. Repeat each test three times and record the results.

Powerful Produce

Objective: Identify which fruits and vegetables are the best electrical conductors.

1. Gather six items: onions, turnips, potatoes, tomatoes, oranges, and lemons.
2. Prepare a pH test kit, a zinc screw, copper wire, and a multimeter.
3. Insert the copper wire into one end of a fruit/vegetable and the zinc screw into the other.
4. Set the multimeter to resistance (ohms) mode; place the red probe on the copper wire and the black probe on the zinc screw. Record the reading.
5. Disconnect the meter, cut open the produce, and test its pH with the kit’s paper strip. Record the pH value.
6. Repeat for all six items.
7. Compile a chart that lists each item’s resistance and pH. Lower resistance indicates better conductivity; note how pH influences the result.

Electricity and Water

Objective: Explore how dissolved substances affect water’s conductivity.

1. Use room‑temperature distilled water and a multimeter set to resistance mode.
2. Measure and record the resistance of plain distilled water.
3. For each additive—salt, sugar, baking soda, vinegar—add 1 ½ teaspoons to 2 cups of distilled water, mix, and test resistance. Add an additional 1 ½ teaspoons each time and record the new readings.
4. Compare results; the lower the resistance, the higher the conductivity.

Electrical Conductivity of Soil

Objective: Determine how soil type and fertilizer influence conductivity.

1. Prepare four beakers labeled: sand, clay, loam, and loam with fertilizer.
2. Dry equal portions of each soil in an oven and weigh 200 g into each beaker.
3. Add 200 ml of water to each beaker; for the “loam with fertilizer” beaker, add 50 ml of liquid fertilizer.
4. Let the soils absorb water for ~30 minutes.
5. Insert two copper electrodes 2 inches apart into a beaker.
6. Connect a 12‑volt battery and a milliammeter across the electrodes: battery positive to one electrode, battery negative to the other, and a third wire to the unused terminals.
7. Record the milliampere reading; the highest reading indicates the best conductivity.
8. Repeat for each soil type and compile a table of results.

These experiments provide clear, hands‑on insight into the science of electrical conductivity while fostering curiosity and critical thinking. Always exercise caution when handling batteries, conductors, and liquids to ensure a safe learning environment.