Thus in a stringed instrument, the three factors that affect and determine the pitch of a note are the length, tension and thickness of the streched string.
Inverse law and Direct law
Inverse law is a case, wherein of two factors, when one is increased, the other decreases in consequence.
Thus of the two factors, pitch and length of a streched string, when the vibrating length of the string is shortened, the pitch is increased and vice versa.
In the flute, the pitch is inversely proportional to its length of the vibrating column of air.
Thus when the vibrating column of air is lengthened by closing more finger-holes from the mouth hole end, the pitch is decreased and vice-versa.
In the mridangam, shorter the area of the drum-head, higher the pitch.
In the human voice, greater the length of the vocal cords, less the pitch. Men's voices are of a lower pitch compared to women's voices, because of the greater length of the vocal cords in men's voices.
Direct law is a case wherein of two factors, if one is increased, the other also increases.
Thus of the two factors, pitch and tension, when the tension is increased, the pitch also increases and vice versa.