Answer
By pressing on the frets, the player reduces the length of the string. Hence, the wavelength of the standing wave decreases, resulting in increase of its frequency and allowing the player to play higher notes. The spacing between frets is designed so that the fractional change in frequency is same from one fret to another to preserve the music intervals of the notes of the scale. As the string gets shorter, the percentage change gets smaller as it is the same fraction a smaller length. If the frets were equally spaced, the note changes from fret to fret would be different as the string becomes shorter.
Work Step by Step
By pressing on the frets, the player reduces the length of the string. Hence, the wavelength of the standing wave decreases, resulting in increase of its frequency and allowing the player to play higher notes. The spacing between frets is designed so that the fractional change in frequency is same from one fret to another to preserve the music intervals of the notes of the scale. As the string gets shorter, the percentage change gets smaller as it is the same fraction a smaller length. If the frets were equally spaced, the note changes from fret to fret would be different as the string becomes shorter.
