Equipment

• Aluminum disks (2)
• Pointer electroscope
• Insulating handle
• Plexiglass rod
• Silk cloth
• Acrylic sheet (optional)

Demo

Begin by attaching the insulating handle to the top of one of the aluminum disks. Attach the other aluminum disk to the top of the electroscope. Next charge the plexiglass rod by rubbing the silk cloth on it for a few seconds. Charge the plate attached to the insulating handle with the rod to induce charge. Grab the insulating handle and place the attached aluminum disk over the disk attached to the electroscope. Do not touch the disks together. The electroscope will deflect.

*The acrylic sheet may be used as a dielectric to keep the disks from touching

Explanation

The aluminum disk attached to the insulating handle acquires a positive charge when brought into contact with the charged plexiglass rod. When the charged disk is placed over the neutral plate, an electric field is formed and negative charge will flow into the disk on the electroscope, inducing positive charge on the bottom of the electroscope. Thus, the electroscope will be deflected.

Written by Madison Harris