Advertisements
Advertisements
प्रश्न
The adjacent diagram shows three different modes of vibrations P, Q and R of the same string.
(i) Which vibration will produce a louder sound and why?
(ii) The sound of which string will have maximum shrillness?
(iii) State the ratio of wavelengths of P and R.
Advertisements
उत्तर १
(i) The loudness or softness of a sound is determined by the amplitude (or intensity) of the wave. In this case the amplitude of R is greater than the amplitude of other vibration modes. Hence, the vibration R will produce more sound than the other two. Louder sound corresponds to the wave of larger amplitude.
(ii) Shrillness or Pitch of a note depends on the wavelength or frequency of wave and here the vibration P has m ore frequency than others. If f is the principle frequency, then
Frequency (P) = 3 f
Frequency (Q) = 2 f
Frequency (R) = f
Hence P has more shrillness than others.
(iii) If the frequency of vibration of R = f, frequency of vibration of Q = 2f, and that of P =3 f.
`Ratio f_P/f_R=3/1`
`f_P:f_R=3:1`
As `fprop1/lambda` hence `lambda_P/lambda_R=1:3`
OR (Another method)
From figure we can say that 3 vibration of P corresponds to 1 vibration of R
i.e `3lambda_P=1lambdaR`
`thereforelambda_P/lambda_R=1/3=1:3`
Therefore, ratio of wavelength of P and R is 1:3.
उत्तर २
(i) Vibration R as its amplitude is high as loudness ∝ A2
(ii) Sound of string ‘P’ will have maximum shrillness as its frequency is maximum.
Pitch ∝ frequency.
(iii) λP : λR = 3 : 1
संबंधित प्रश्न
In the diagram below, A, B, C, D are four pendulums suspended from the same elastic string PQ. The length 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
1) Name the type of vibrations taking place in pendulums B and D?
2) What is the state of pendulum C?
3) State the reason for the type of vibrations in pendulum 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?
In following figure shows two tuning forks A and B of the same frequency mounted on two separate sound boxes with their open ends facing each other. The fork A is set into vibration.
- Describe your observation.
- State the principle illustrated by this experiment.
When a troop crosses a suspension bridge, the soldiers are asked to break steps. Explain the reason.
(i) Define resonant vibrations.
(ii) Which characteristic of sound, makes it possible to recognize a person by his voice without seeing him?
On keeping the stem of a vibrating tuning fork on the surface of a table, a loud sound is heard. Give reason.
What do you mean by resonance? When does resonance occur?
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?
Explain a person walking past a railway line, in the middle of night hears a ringing sound along with the sound of his footsteps.
