Advertisements
Advertisements
Question
Why are the stringed instruments like guitar provided with a hollow sound box?
Advertisements
Solution
The sound box is constructed such that the column of the air inside it, has a natural frequency which is the same as that of the strings stretched on it, so that when the strings are made to vibrate, the air column inside the box is set into forced vibrations. Since the sound box has a large area, it sets a large volume of air into vibration, the frequency of which is same as that of the string. So, due to resonance a loud sound is produced.
APPEARS IN
RELATED QUESTIONS
Define the resonance phenomenon.
In the diagram below, A, B, C, D are four pendulums suspended from the same elastic string PQ. The lengths of A and C are equal to each other, while the length of pendulum B is smaller than that of D. Pendulum A is set into a mode of vibrations.
- Name the type of vibrations taking place in pendulums B and D.
- What is the state of pendulum C?
- State the reason for the type of vibrations in pendulums B and C.
What are mechanical waves?
The diagram above shows a wire stretched over a sonometer. Stems of two vibrating tuning forks A and Bare touched to the wooden box of the sonometer. It is observed that the paper rider (a small piece of paper folded at the centre) present on the wire flies off when the stem of vibrating tuning fork B is touched to the wooden box but the paper just vibrates when the stem of vibrating tuning fork A is touched to the wooden box.
1) Name the phenomenon when the paper rider just vibrates.
2) Name the phenomenon when the paper rider flies off.
3) Why does the paper rider fly off when the stem of tuning fork B is touched to the box?
Differentiate between the forced and resonant vibrations.
In fig. , P, Q, R and S represent test tubes each of height 20 cm which are filled with water upto heights of 10 cm, 14 cm, 16 cm and 18 cm respectively. If a vibrating tuning fork is placed over the mouth of test tube Q, a loud sound is heard.
(i) Describe the observations with the tubes P, R and S.
(ii) Give the reason for your observation in each case.
(iii) State the principle illustrated by the above experiment.
Explain why stringed musical instruments, like the guitar, are provided with a hollow box.
The rearview mirror of a motorbike starts vibrating violently at some particular speed of the motorbike. What is the name of the phenomenon taking place? Why does the happen?
A vibrating tuning fork is placed over the mouth of a burette filled with water. The tap is opened and the water level gradually falls. It is observed that the sound becomes the loudest for a particular length of the air column. What is the name of the phenomenon taking place when this happens? Why does the sound become the loudest?
When a tuning fork, struck by a rubber pad, is held over a length of the air column in a tube, it produces a loud sound for a fixed length of the air column. Name the above phenomenon. How does the frequency of the loud sound compare with that of the tuning fork? State the unit for measuring loudness.
