Final answer:
A stationary wave in air is exemplified by the standing waves formed inside a musical instrument like a flute, which result from resonance and produce distinct musical notes.
Step-by-step explanation:
A real-life example of a stationary wave in air is the resonance of air inside a musical instrument like a flute. When the flute is played, sound waves are produced within the body of the instrument. The air at both ends of the flute has fixed boundaries, leading to the creation of stationary waves.
The sound we hear is due to these standing waves, which are a type of wave where certain points (nodes) do not move, and other points (antinodes) vibrate with maximum amplitude. The pitch of the note produced depends on the frequency of the standing wave, which in turn is related to the length of the air column inside the instrument. The phenomena of standing waves in musical instruments illustrate the important principle of quantization, where only specific frequencies of standing waves are allowed within the system with fixed boundaries.