Bell in Bell Jar

Without air or matter, sound waves cannot travel and therefore cannot be heard. This bell jar effectively demonstrates this concept using a battery-operated buzzer housed inside the jar. When the buzzer is placed beneath the jar and a vacuum is created inside the jar, students will observe a total absence of sound. Once the air is returned to the jar, the sound of the buzzer can be heard once more. The activity requires a vacuum pump & plate, not included.