Homemade Electrophorus

A simple electrophorus device made from a foam plate, aluminum pie plate, and other common materials demonstrates static electricity, voltage, positive and negative charges, resistance, and electron transfer.

1. Rub a foam plate with a wool sock or rag to charge it negatively by friction.
2. Place an aluminum pie plate (with a foam cup handle) on top of the charged foam plate.
3. Briefly touch the aluminum plate with your finger to transfer electrons—listen for a spark.
4. Lift the aluminum plate using the cup handle and bring your finger close again to observe further sparks.
5. Repeat several times, noting how the aluminum plate can be recharged by contact with the foam plate.
6. Suspend a small piece of foil-covered straw on a thread so it can swing freely near the plate. Observe how it is attracted or repelled depending on charge.
7. Hold a neon bulb near the conductor or plate; watch it flash as electrons discharge through the bulb.
8. Test further by bringing a pointed object (like a needle) near the conductor to demonstrate charge leakage through air ionization.

You Can Build an Electrophorus - The Dock for Learning:

Electrophorus - Electric and Magnetic Fields:

📄 Charging an Electrophorus by Induction Using a Negatively Charged Object - The Physics Classroom: https://www.physicsclassroom.com/mmedia/estatics/epn

• Try different insulating surfaces instead of a foam plate.
• Vary the distance between the conductor and your finger to demonstrate resistance and voltage breakdown.

• This demonstration involves static discharges that can give mild shocks - avoid people with pacemakers or sensitive electronics nearby.
• Only use low-energy static sources (foam, wool, foil) - do not connect to power outlets.
• Handle needles and pins carefully to avoid injury.
• Keep neon bulbs or fragile components away from rough handling.

• Why does rubbing the foam plate with wool create a static charge? (Electrons transfer from one material to the other, leaving an imbalance.)
• Why can the aluminum plate repeatedly gain charge without re-rubbing the foam plate? (Electrostatic induction allows charges to redistribute each cycle.)
• What role does the neon bulb play? (It lights up when electrons discharge through the gas inside, showing current flow.)
• Why does a pointed needle discharge more easily than a blunt object? (Electric fields are stronger at sharp points, causing ionization of air.)
• How does this experiment illustrate the concepts of voltage, current, and resistance? (Voltage is the potential difference, current is electron flow during discharge, and resistance is the opposition to flow across the air gap.)