(5B20.15) Faraday “Ice Pail”
Rub the PVC tube with the animal fur and touch the inside of the metal cup with the tube. Take the proof plane and touch the inside of the metal cup with the plane. Then touch the black disk of the electroscope with the proof plane. Do this a few times to verify that there is no charge inside the cup. Now with the proof plane touch the outside of the metal cup. Do this a few times. The electroscope will show charges on the outside of the cup.