Principle of Superposition of waves
When two or more waves simultaneously pass through a point, the disturbance at the point is given by the sum of disturbances each wave would produce in absence of the other wave(s).
Laws of Transverse Vibrations of a String: Sonometer
1. Law of length: the fundamental frequency of vibration of a string (fixed at both ends) is inversely proportional to the length of the string provided its tension and its mass per unit length remain the same.
v α 1/L if F and µ are constant.
2. Law of tension; the fundamental frequency of a string is proportional to the square root of its tension provided its length and the mass per unit length remain the same.
v α √(F) if L and µ are constant.
3. Law of mass: The fundamental frequency of a string is inversely proportional to the square root of the linear mass density, i.e., mass per unit length provided the length and the tension remain the same.
v α 1/ √(µ) if L and F are constant.