Purpose:Demonstrate the effect of a sounding board.
Description:If a tuning fork is struck and held in the air, it is not very loud, due to lack of good coupling between the tuning fork and the air. On the other hand, if the bottom of the tuning fork is held firmly in contact with the lecture table or other large surface, it will be much louder. The vibrations are transferred much more efficiently from the tuning fork to the table (the sounding board) and then from the table to the air. Invite students to speculate about the effects of different surfaces in the classroom.