Welcome back! Today we’re checking out a classic demonstration and party trick: the triboelectrically charged balloon, demonstration J1-05.

 

Triboelectricity is the phenomenon whereby some combinations of materials become electrically charged from contact and separation. We sometimes refer to this as “charging by friction,” though this is not really accurate – simple contact causes the charge transfer, not movement, but rubbing the materials together often allows more surface contact and thus more charge transfer.

Once an object carries an imbalance of charge, such as this balloon picking up charge from some fabric or your hair, it will tend to be attracted to objects with a different charge, or even to neutrally charged objects that have enough charge mobility to let an imbalance form via induction.

This simulation, in the PhET Collection and the University of Colorado, shows graphically what happens. Touching the balloon to some fabric causes it to pick up an imbalance of charge. While close to the fabric, it tends to cling there, as the unlike charges attract. Once brought near the wall, though, we see an induced imbalance of charge form, as charges like that on the balloon are slightly repelled and charges unlike that on the balloon are slightly attracted, causing the balloon to cling to the wall in electrostatic attraction.