Bell in Jar Experiment

• An electric bell rings inside a sealed glass bell jar. As the hand pump draws the air out, the ringing grows fainter and fainter even though the hammer can still be seen striking the gong. Let the air back in and the sound returns, proving that sound needs a medium to travel and cannot pass through a vacuum.
• Electric bell inside a glass bell jar, wired to terminals on the lid
• Hand-operated pump with stop-cock valve and sealed jar plate
• Mounted on a wooden base for classroom demonstrations