3. STRING VIBRATION
The tention and the length of the string is the fundamental frequency at which the string vibrates. So, we can place a finger on the fingerboard to change it length and the vibrate mode. Therefore, we can produce different scale of sound.
from UNSW homepage
The violin is capable of generating a great variety of sounds. It can produce very sharp sounds when the length of a string is reduced by pressing a finger down on it. Also, the violin is unlimited sound so it is difficult to play.
from Team 27178 homepage
Also, string vibration has connection with the tuning process. The violin is turned by adjusting the tension of the string to give the right fundamental frequency. Shortening the length of string that is vibrating increases the frequency of vibration and the pitch. To go up an octave on the violin on shifts up half way to the bridge from the previous note.