Bell in a Vacuum

It is common knowledge that for sound to travel, there has to be a medium for it to pass through, be it air, water or a solid. It follows that in a vacuum sound can not exist. This is something that is ignored in most science fiction movies.

The bell in a vacuum chamber is a classic demonstration that sound can not travel through a vacuum. Strangely though, it was something that I had never witnessed, so I decided to set it up in the vacuum rig.

The bell-jar starts out evacuated with the bell operating. If you look carefully you should be able to
see the bell shaking. After two seconds, a bang is heard as the solenoid air admittance valve opens. Air can then be heard rushing into the chamber. About 12 seconds into the movie, the bell can just be heard. At the end of the movie the chamber is at atmospheric pressure and the bell at full volume.

Category:

Science & Technology

Tags:

• Vacuum
• Space
• Sound

[kmdental36]

Good Job.

Way to think outside of the box. Or better yet inside of the jar. Hey I was wondering that maybe it isnt that its not traveling through the vacuumed air as well as it is just hitting a higher or no autible frequency through the vacuum. Please let me know what you think. It would be nice to have a gauge that can pick up higher autible frequency. Thanks. Keep up the science.

[teralabUK]

Sound has to have some medium to travel through. In a vacuum there simply can't be any sound. Most science fiction movies ignore this inconvenient fact.

[CanberraUser]

Science fiction movies LISTEN UP!

[immahackinmahlazah]

PLEASE let dat not be da school bell

[LoquaciousApe]

@mlchiLCA You misunderstand the science behind this. Sound waves are simply ripples in mediums. Producing sound waves in a vacuum would be like throwing a pebble onto the ground and expect it to produce water ripples. There's no water, ergo no ripple. Similarly, no medium in a vacuum -- no sound waves produced.

[mlchiLCA]

@teralabUK

thats by our standards...maybe it does travel at a frequency that earthly beings cant hear nor gauge with current technology

[jordanskatergirl]

:D

I did this for a science project in elementary school. :P

[predatortheme]

i think the sound traveled throught the object that holds the bell :<

[burchified]

There's no such thing as a perfect vacuum. Therefore, there will still be some amount of propagation.

[FoSbaKiaS]

HIDE! THA TRAIN'S COMIN!!!

[TheGavinch]

Maybe the seal isn't perfect, or maybe its going through the solids...like through the stand and the base of the vacuum itself...idk, that's just a thought.

[DayLight95]

its a bell in a bell