During an investigation about sound, students place an alarm clock that is ringing in a Bell Jar as seen in the picture below. Prior to turning on the Bell Jar Pump (which removes the air from the jar) the teachers ask the students to predict what will happen. Each student gives an explanation: Student A: The sound will not be heard because the bell cannot move when all of the air in the bell jar has been removed. In order to hear sound, there must be a medium.

Student B: The sound cannot be heard because sound requires a medium. While the bell is still moving, all the air has been removed and therefore there is no medium.

Student C: The sound can be heard because the bell can move even though all of the air in the bell jar has been removed. In order to hear sound, there must be a medium and the bell is the medium

Student D: The sound cannot be heard because sound requires a medium. Since there will be no air, the bell will not move and the moving of the bell requires air

A. Student B

B. Student A

C. Student C

D. Student D