Edison effect: Electrons are cast off from hot filament.

Edison effect: Electrons are cast off from hot filament. The Edison effect demonstrates that electrons are emitted from a hot filament. To operate the demo, select 'Edison Effect' with the knob on the top of the black box. The filament of the tube is heated, and the electrons that come off are collected by the anode on the top of the tube. The current that flows is shown with the projection ammeter. The six volt bias switch should be in the center (off) position.