Which of the following phenomena is used by the musicians to tune their musical instruments?
A) Interference
B) Diffraction
C) Beats
D) Polarisation

Hint: We will be evaluating the meaning of the given phenomenon and then check which among these is used by the musicians to tune their musical instruments.

Complete step by step answer:
A) Interference: It is a phenomenon where two or more waves superimpose each other and the amplitude gets modified (increases or decreases and in some cases remains the same).
B) Diffraction: It is the phenomenon of bending of waves when they encounter any obstacle in their path of propagation.
C) Beats: It is the phenomenon of interference of two waves of nearly equal frequencies and amplitudes. The sound wave generally has an average frequency of the original frequencies.
D) Polarisation: Light can vibrate both perpendicular and parallel to the direction of propagation, but when polarised with a polariser, its movement is restricted either to perpendicular or to horizontal.
🡪The phenomenon of beats is useful for musicians to tune their instruments. It can be diagrammatically represented as:



Both the waves are of similar frequencies and amplitudes, beats formed by these are:

Note:The beat phenomenon can be also be used to hear some ultrasonic sounds (inaudible to the human ear)
The ultrasonic sound waves produced by bat or dolphin can be superimposed with a wave of different frequency so as to convert it into an audible beat.