We can see the bell, so the experiment proves that electromagnetic waves (e.g., visible light) can travel through a vacuum. We can’t hear the bell, so sound waves do not travel through a vacuum, i.e., sound needs a medium to be transmitted.
You can help us out by revising, improving and updating this answer.Update this answer
After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.