By William Hirsch | Updated March 24, 2022
Creating an electric field without using magnets is straightforward when you harness the principles of a parallel‑plate capacitor. By separating two oppositely charged metal plates, you generate a uniform electric field between them—a fundamental component of countless electronic devices.
A simple parallel‑plate capacitor using everyday materials. The electric field (E) between the plates can be calculated as E = V/D, where V is the voltage supplied by the battery and D is the separation in meters. The field is measured in volts per meter (V/m).
Using a metric ruler, draw a straight line 5 cm from the left edge of each cardboard sheet. The line should run parallel to the edge to ensure the plates remain level.
Fold each sheet along the marked line so that the cardboard stands upright on the table, creating a 25 × 25 cm surface area for the metal coating.
Cover the top surface of each sheet with aluminum foil, smoothing it to minimize air gaps. Fold foil over the edges so that both sides of the cardboard are coated.
Tape the two sheets to the table, face to face, with a 0.5 cm gap between them. The foil-coated sides should be toward each other.
Attach a wire from the negative terminal of a 9‑volt battery to one foil surface, and a second wire from the positive terminal to the opposite foil. The plates will now carry opposite charges.
With the plates charged, an electric field exists across the 0.5 cm gap. For a 9‑volt battery, the field strength is E = 9 V / 0.005 m ≈ 1.8 × 10³ V/m.
For safety, avoid touching the foil surfaces while the battery is connected. This simple experiment demonstrates the basics of electrostatics and is a valuable hands‑on learning tool.
