Figure shows two tuning forks A and B of the same frequency mounted on two separate sound boxes with their open ends facing each other. The fork A is set into vibration. (a) Describe your observation. (b) State the principle illustrated by this experiment.

The vibrating tuning fork A produces forced vibrations in the air column of its soundbox. The vibrations in the soundbox have a significant amplitude due to the huge surface area of air in the soundbox. They are conveyed to the fork B’s soundbox. B’s air column begins to vibrate at the same frequency as fork A. Because the frequency of these vibrations is the same as the fork B’s natural frequency, the fork B takes them up and begins vibrating under resonance.

When you shake the tuning fork A, the other tuning fork B begins to vibrate as well. Vibrations are created in the second tuning fork B due to resonance.