What would you observe if the air was removed from a bell jar containing a ringing mobile phone?

You wouldn't observe anything, but the ring would be very hard to hear (a little bit of the sound might be conducted out through the base of the enclosure.

If the phone was somehow suspended in the vacuum, you would not hear it ring. It has nothing to do with light... not sure where that came from.

If the phone is in contact with the jar, you will still here something as the phone will vibrate the glass and create some sound.

.Imagine that light energy couldn’t travel through empty space. What would you observe if the air was removed from a bell jar containing a ringing mobile phone?