characteristics of sound waves
characteristics of sound waves
characteristic of a sound wave:- A sound wave can be described by five characteristic these are
- Wavelength
- Amplitude
- Time period
- Frequency
- Velocity
Wavelength:-
- The distance between the two nearest crest of a wave is called its wavelength.
- The minimum distance in which a sound wave repeats itself is called its wavelength.
- In other words it is the length of one complete wave.
- The distance between neighboring crest and trough is equal to half of the wavelength.
- Wavelength is denoted by lambda ( ƛ ).
- S.I unit of wavelength is 'm' .
Amplitude:-
- The height of the crest or the depth of the trough of a wave is called amplitude.
- It is denoted by 'A'.
- Its S.I unit is 'm' .
- The amplitude of a wave is a measure of its energy hence the greater of the amplitude of a wave the greater is the energy.
Frequency:-
- The number of wave produced per second is called frequency.
- Frequency is denoted by 𝞶 or read as (nu) or f.
- The unit of frequency is Hz.
- example:- If 30 waves cycle are produced in one second then the frequency of the periodic wave is 30 Hz or 30 cycle/s.
- Note:- Frequency of a wave does not depend upon the nature of the medium through which it is travels hence the frequency of the wave remains the same as like solid, liquid and gas.
Time period:-
- The time required to produce on complete wave is called the time period of the wave.
- The S.I unit of time period is second 's' .
- It is denoted by letter 'T'.
Wave velocity:-
- The distance traveled by wave in one second is called wave velocity.
- It is denoted by letter 'V'.
- The S.I unit of wave velocity is m/s.
- The velocity of the wave depends upon the material medium through which they travels.
- speed of sound in air 343 m/s at 20 degree C.
- Speed of sound depend on medium as I say in the previous line.
Relation between Time period and its frequency
We know that time required to complete one wave is called time period.
Number of wave produce in 'T' sec. = 1
Number of wave produce in 1 sec. = 1/T
but,
we know that No. of wave produce in one second is called frequency,
ஃ Frequency = 1/ time period
F = 1/ T
Relation between wave velocity, Frequency and wavelength for a periodic wave.
velocity of wave = wavelength х Frequency
Sonic Boom:-
When a body moves with a velocity which is greater than the speed of sound in air then it is said to be travelling at supersonic speed. ( such as jet fighter plane or bullet gun ), and when they produce a sharp loud sound called a sonic boom.
Sound depends on many things.
- Pitch
- Loudness
- Quality of musical sound
Pitch:-
We can distinguish between a man's voice and a women's voice of the same loudness even without seeing them. this is because a man's voice and a women's voice differ in pitch.
A man's voice is flat having a low pitch, whereas a women's voice is shrill having a high pitch.
- Pitch is that characteristic of sound by which we can distinguished between different sound of the same loudness.
- Pitch of the sound depends upon the frequency of the vibration.
- Pitch of the sound is directly proportional to its frequency.
loudness:-
- The loudness of sound is a measure of the sound energy reaching the ear per second.
- Loudness of the sound depends on the amplitude of sound wave.
- The greater the amplitude of sound wave , louder the sound will be.
- The S.I unit of loudness of sound is decibel. ' dB '.
- The softest sound which human ears can here is said to have a loudness of zero decibel.
- The loudness of sound of people talking quietly is about 65 decibel.
Reflection of sound
- The bouncing back of sound when it strikes on a hard surface is called reflection of sound.
- Sound waves are much longer than light wave so they required a much large area for reflection.
