Take a tuning fork which is a rectangular rod of steel bent in U shape, with a metallic stem at the bend. Strike it’s one arm on a rubber pad and bring it near a table tennis ball suspended by a thread as shown in the figure below.
It is noticed that as the arm of the vibrating tuning fork is brought close to the ball, the ball jumps to and fro and sound of the vibrating tuning fork is heard. When it’s arms stops vibrating, the ball becomes stationary and no sound is heard.
Hence, we can say that the sound produced by a tuning fork is due to vibration of it’s arms.
