Bell in a Jar Experiment – Improved Demonstration Model

This upgraded version of the classic Bell in a Jar Experiment provides a safe, reliable, and effective way to demonstrate how sound relies on air to travel. Featuring a redesigned base with a durable rubber sealing sheet, the unit creates an excellent vacuum seal without the need for vacuum grease—ideal for regular classroom use.

The lightweight aluminium pump plate is mounted on a sturdy tripod base and includes a central evacuation pillar with a tube connection, allowing air to be removed efficiently from the bell jar. A built‑in stopcock enables the vacuum chamber to be sealed, maintaining the vacuum even after the pump is switched off.

The robust acrylic bell jar offers high impact resistance and improved safety in the unlikely event of implosion. Designed with a flat flange, it forms a strong, reliable seal against the pump plate. Inside, the bell is suspended by wires to minimise sound conduction through the structure, ensuring students hear the true effect of decreasing air pressure.

As the air is evacuated, the bell becomes progressively quieter—clearly demonstrating how sound waves need a medium to travel. When the stopcock is closed and air is gradually reintroduced, the bell becomes louder again, delivering a memorable visual and auditory demonstration for students.

The high‑quality bell operates on 4–6V AC or DC. A suitable vacuum pump and heavy‑walled vacuum tubing are required (recommended: electric vacuum pump, code 0951).

Key Features

• Improved, classroom‑safe Bell in a Jar demonstration
• Rubber-sealed base eliminates need for vacuum grease
• Lightweight aluminium pump plate on a heavy tripod base
• Stopcock allows chamber to be sealed after evacuation
• Acrylic bell jar offers excellent safety and impact resistance
• Bells suspended by wires to reduce sound conduction
• 4mm sockets on top bung for electrical connection
• Bell operates on 4–6V AC/DC
• Ideal for demonstrating how sound cannot travel in a vacuum
• Requires vacuum pump and heavy‑walled tubing (sold separately)

Dimensions

Ideal for School Science Lessons & Physics Demonstrations

Perfect for KS3, GCSE, and A‑Level physics, this demonstration vividly shows students that sound needs a medium to travel. It is ideal for:

• Teaching sound waves and particle vibration concepts
• Demonstrating vacuum principles in pressure and gas lessons
• Supporting practical physics demonstrations on waves and energy transfer
• Providing a memorable, interactive visual and auditory experiment

Safe, reliable, and designed for educational use, this Bell in a Jar setup is an essential classroom resource for demonstrating how sound behaves in low‑pressure environments.