Sound Wave is characterized by
- Frequency
- Amplitude
- Wavelength
- Time period
- Speed
Let's study these one by one
What is Amplitude
It is maximum displacement of a vibrating object from its central location
Explanation
We know that sound is produced due to vibration of particles (To and Fro Motion)
In to and fro motion, an object moves from its central position
More it moves from its central position, more is the amplitude
Less it moves from its central position, less is the amplitude
Note - More Amplitude means More Loudness of Sound
Loudness is directly proportional to the square of Amplitude
If amplitude becomes double, loudness becomes 4 times
If amplitude becomes half,loudness becomes ¼ times
Note:- Roaring of lion can be heard over long distances because it has higher amplitude
Before we study frequency, lets learn what frequency means
What is one complete oscillation?
The change in density from the maximum value to the minimum value , then again to the maximum value makes one complete oscillation.
Time Period of Sound
The time taken by the wave for one complete oscillation is called the time period
It is denoted by t.
It's SI unit is second (s)
Frequency of Sound
The number of oscillations made in one second is called the frequency of the sound wave.
It is denoted by nu (ν)
Its SI unit is Hertz (Hz)
Explanation
We know that sound is produced due to vibration of particles(To and Fro Motion)
More times it moves in one second,more is the frequency
Less times it moves in one second,less is frequency
Example 1
Suppose if vibration of sound is 50 vibrations per second, it means its frequency is 50 hz
Note - Frequency determines shrillness or pitch of sound
More the frequency, more the shrillness of sound
Less the frequency, less the shrillness of sound
Example 1
- Voice of Baby is of high pitch
- Voice of grown up man is low pitch
Example 2
- Chirping of Bird is of high pitch
- Roaring of lion is of low pitch
Relationship between Time Period and Frequency
Time Period = 1/Frequency
Example
Suppose Frequency of an Object is 20 Hertz
It means that it makes 20 vibrations in 1 second
Time taken for 1 vibration=1/20=0.05 seconds
Wavelength of Sound wave
Check it here
Speed of Sound wave
Check it here
Questions
Question 1 Page 166 (Right Top) - What are wavelength, frequency, time period and amplitude of a sound wave?
