Page 12 - 10-phy-11 Sound

11. Sound eLearn.Punjab

Animation 11.5: Echo sounder
Source & Credit : punaridge

The speed of sound in air is affected by changes in some Table 11.2
physical conditions such as temperature, pressure and
humidity etc. Speed of sound in various media
The speed of sound in air is 343 ms-1 at one atmosphere
of pressure and room temperature (21°C). Medium Speed (ms-1)
The speed varies with temperature and humidity. The
speed of sound in solids and liquids is faster than in Gases
air. Following relation can be used to find the speed of
sound. Air (0oC) 331

v = fλ ........ (11.6) Air (25oC) 346
where v is the speed, f is the frequency and λ is the
wavelength of sound wave. Air (100oC) 386

Example 11.2: Calculate the frequency of a sound wave Hydrogen (0oC) 1290
of speed 340 ms-1 and wavelength 0.5 m.
Solution: Given that; speed of waves v = 340 ms-1 Oxygen (0oC) 317

Wave length λ = 0.5 m Helium (0oC) 972
Using the formula v = f λ
Liquids at 25oC
Putting the values
f = 340 ms-1 /0.5m = 680 Hz Distilled water 1498

Sea water 1531

Solids 25oC

Wood 2000

Aluminum 6420

Brass 4700

Nickel 6040

Iron 5950

Steel 5960

Flint Glass 3980

12 V: 1.1