Question

The sound box of a sonometer increases
A) speed of sound.
B) sound intensity.
C) wavelength of sound.
D) sound frequency.

Answer 1

Hint
Sonometer is an instrument which works on the principle of resonance and it reads the resonant frequency. Without the sound box, the intensity of sound is not proper or fixed so the sound box helps in amplifying the sound.

Complete step by step answer
Sonometer is a device for demonstrating the relationship between frequency of the sound produced by a plucked string, and the tension, length and mass per unit length of the string. For small amplitude vibration, the frequency is proportional to:
   a) The square root of the tension of the string,
   b) The reciprocal of the square root of the linear density of the string,
   c) The reciprocal of the length of the string.
Although sonometer establishes the relationship among all these terms it has a component named sound box which amplifies the sound. In other terms it adjusts the intensity of sound which is being heard or the level of sound being heard.

Note
Sonometer is an important instrument which works on the principle of resonance. The famous sonometer wire experiment will be read in the last chapter of physics which will also show the definite relationship among them which is, $v = \sqrt {\dfrac{T}{{\mu \;}}} $ where v is the velocity of sound in that medium. T is the tension produced in the string and $\mu \; = \dfrac{m}{l}$ which is the mass per unit length of the string.