# Characteristics of a sound wave • Sound wave is longitudinal wave consisting of compression and rarefaction traveling through a medium
• To describe a sound wave we need to know five terms
• Time Period,Frequency,Wavelength,Amplitude,and Velocity In the Above Image

• Sound Wave ABCDE and EFGHI .
• It starts from position A (normal density position) and compress along ABC and Rarefaction along CDE
• Again it returns to its normal position E
• Thus The ABCDE portion shows a complete Wave

### Wavelength-

• The Minimum Distance in which a sound wave repeats itself is called its wavelength
• It is denoted by the symbol  lambda  λ
• The Combined length of one compression and rare fraction is called its wavelength
• In the above figure the combined length of AC and CE means the length ACE is the wavelength
• The SI unit of wavelength is Meter

### Amplitude

• When a wave passes through a medium ,the particles of the medium gets displaced temporarily from their original position
• In the Figure PB is the Amplitude
• The maximum displacement of the particle of the medium from their original undisturbed position is called amplitude
• The SI unit of Amplitude is Meter

### Time Period

• The Time required to produce one complete wave is called time period
• You can say the time taken to travel from Point A to point E is the time period
• The Unit of time period is Second

Frequency

• The Number of complete cycles produced in one second is called Frequency
• The Unit of frequency is Hertz Hz.

Also F= 1/t

Where Frequency = 1/ Time Period

Velocity Of Wave(Speed of wave)

• The distance traveled by a wave in one second is called its velocity.
• Its unit is M/S

## The Relationship between frequency wavelength and velocity ### Example

1. If 25 sound waves are produced per second,what is the frequency in hertz.

Ans. As the name Says Frequency is equal to number of waves produced in a second .hence frequncy is equal to 25 hertz.

Now Another Problem

2.The Wavelength of  a sound emitted by a source is 1.7 × 10 -2 m. calculate the Frequency of the sound if its velocity is 343.4 m/s .

Solution

The Relationship between frequency wavelength and velocity is given by

v= f ×λ

v= velocity of the wave

f=frequency

λ= Wavelength

Velocity of the wave = Frequency × Wavelength

So     343.4 = f ×  1.7 × 10 -2 m

f = 2.02 ×  104 Hz.