The Proof Plane is used to transfer electrostatic charge from one body to another, or to remove a small amount of charge from a larger body and to then evaluate it with an electroscope. Our design features a metallized sphere measuring 3.8cm in diameter mounted on an 18cm acrylic rod. A spherical shape is used because this geometry holds the greatest charge and retains it for the longest time.
To demonstrate, you can touch the sphere of the Proof Plane to the inside of a charged Hollow Sphere (N-121) and then bring it near an electroscope to show that no charge is present. Conversely, the Proof Plane can be touched to the ouside of the charged Hollow Sphere and then brought near the electroscope to show that a charge has been transferred to the Proof Plane
Sphere: 3.8 cm diameter
Length: 18 cm