8th Class Science Sound Components of Sound Wave

        Components of Sound Wave

The sound wave has got the following components:  

           Amplitude

The maximum displacement of the waves from the mean axis is known as amplitude. The amplitude of the waves tells us about the intensity of the sound.

We can increase or decrease the amplitude of vibration according to our wish.

            Time Period

Time taken by the wave to complete on vibration is called time period. It is denoted by 'T. It can also be defined as the time taken by the sound wave to complete one oscillation.

           Frequency of Vibration

It is the number of vibration made by the wave in one second. It is measured in Hertz. If an object makes one vibration in one second then its frequency is one Hertz. To find the frequency of a wave, we always divide the total number of frequency in a given time, by the total time taken.

            Wavelength

The distance between any two consecutive crest or trough is called wavelength.

            Relation between Frequency and Time Period

The frequency of vibration is given by the number of vibration in one second, that is, the frequency is equal to the reciprocal of the time period.

\[Time\text{ }period=\frac{1}{frequency}\]

\[T=\frac{1}{f}\]

           Relation between Wavelength and Frequency

If V is the velocity of the wave and^, is the wavelength of the wave, the velocity of the wave is given by:

Velocity = Wavelength x Frequency

V=Xxf

        The frequency of the sound traveling with a velocity of 680 m/sec and a wavelength of 2 m is:

(a) 340 Hz

(b) 240 Hz

(c) 520 Hz

(d) 680 Hz

(e) None of these

Answer: (a)

Explanation

The frequency of the sound can be calculated by using the relation,\[v=\lambda \times f\].

On calculation it is found to be 340 Hz.

Therefore, option (a) is correct and rest of the options is incorrect.

       The maximum upward elevation of the wave about its mean position is called:

(a) Trough

(b) Crest

(c) Wavelength

(d) Frequency

(e) None of these

Answer: (b)

Explanation

The maximum upward displacement of the wave about its mean position is called crest.