Characteristics of a Sound Wave

Topics

• Frequency
• Amplitude (A)
• Time period (T)
• Wavelength (λ)
• Wave velocity
• Pitch

Notes

A sound wave is characterized by three factors:

• Amplitude

• Frequency

• Speed

Amplitude:

The value of the maximum or minimum disturbance caused in the medium is called the Amplitude of the Sound.
Amplitude defines if the sound is loud or soft.

Frequency (f):

The number of oscillations per unit time is called the Frequency of a Wave (Number of compressions + the number of refractions per unit time). F = 1 / T
SI unit: Hertz (Hz)

Speed of sound:

The distance by which a compression or refraction of a wave travels per unit time is called as Sound’s Speed.
SI unit: metres/seconds
v = wavelength / time = λ/T = λ*F
Speed of Sound in air = 343 m/s

Compression:

The compression region is represented by the upper part of the wave curve. It is a region where particles cluster together. The density, as well as pressure, is always high in this region.

Refraction(R):

A refraction is represented by the lower part of the wave curve. It is a region where the particles separate out. Refraction region always has lower pressure.

Crest:

It is the peak of the curve.

Trough:

It is the crust of the curve

Wavelength (λ):

The distance between two consecutive compressions or refractions is called Wavelength.

SI unit: metre (m)

Time Period (T):

The time taken between two consecutive compressions or refractions to cross a fixed point is called Time Period of the Wave.

In other words, the time taken for one complete oscillation through a medium is called a Time Period.
SI unit: second (s)

Pitch:
Pitch of a sound depends upon:
1. the frequency of the sound
2. size of the object producing the sound
3. type of the object producing the sound

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