Hollow Conducting Sphere
To demonstrate that the charge resides on the outside of a conductor.
Hollow conducting sphere, positive and negative charging materials, proof plane, electroscope and point◙projection source.
Charge the sphere several times by scraping charge off a rod, either positive or negative. Touch the proof plane several times to the outside of the sphere and then to the electroscope. The electroscope charges, indicating that there is charge on the outside of the sphere. Touch the proof plane several times to the inside of the sphere and then to the electroscope. The electroscope does not charge, indicating that there is no charge on the inside of the sphere. Repeat for the outside to demonstrate that the sphere is still charged.
Richard M. Sutton, Demonstration Experiments in Physics, E-28 Distribution of Charge on Conductors, 263. ◙Instruction for Use of No. 2025 Hollow Conducting Sphere, Welch Scientific Co., Skokie, IL.