Immagini

DESCRIPTION

The electric bells apparatus was designed by Andrew Gordon (1712-1751) to demonstrate that opposite charges attract and the same charges repel. The apparatus consists of two external bells connected by a common metallic base, while a third one in the center having a glass base is isolated from the rest. Two pith balls are suspended from the top of the supports of the external bells.

To perform the experiment the rod of the central bell is connected to an electrostatic machine. The pith-balls, when charged by induction, are attracted by the central bell that, when hit, emits a sound.

When the central bell is hit, the pith balls are charged to the same sign and are immediately repulsed. In this way the balls strike the external bells, emitting sound again and becoming discharged, giving in this way a new start to the cycle: the process continues until the central rod is disconnected from the electrostatic machine.

Dati Catalografici