Question

An air-box attached to a musical instrument increases the:
A. Pitch of the sound
B. Intensity of the sound
C. Quality of the sound
D. Shrillness of the sound

Answer 1

Hint: Recall the basic information about the air box and function of the air box attached to the musical instrument. Also recall the information about how sound is produced in a musical instrument. Hence, check which factor related to the musical instrument changes when the air box is attached to the musical instrument.

Complete answer:
A musical instrument is the instrument which produces sound when it is played by using the threads, strings or buttons attached in it. An air box attached to a musical instrument is an open air box which helps to improve the sound output from the musical instrument. This air box allows more air particles in the medium for vibration which helps in sound production and transfer of the sound from the musical instrument to the surrounding medium.

When we pluck the wires or threads in an instrument, the air particles around the wire or the thread vibrate according to the vibration of the wire or thread. If the amplitude of vibration of the wire is large then the amplitude of vibration of the air particles will also be large.The amplitude of vibration of the air particles is the maximum distance of the air particles from their mean positions in the medium. The amplitude of vibration of the thread is proportional to the intensity of the sound.

If the amplitude of vibration of the wire or thread increases, the amplitude of vibration of the air particle increases and the intensity of the sound from the musical instrument also increases and we hear a large sound. Therefore, the air box attached to the musical instrument increases the intensity of the sound.

Hence, the correct option is B.

Note: The students should not get confused between the intensity of the sound and pitch of the sound. The intensity of the sound depends on the amplitude of vibration of the air particles and the pitch of sound depends on frequency of the sound. The air box attached increases the amplitude of vibration by increasing the air particles for vibration and not frequency of vibration of the air particles.