The wavelength of a sound wave is directly related to the speed of sound in the medium and the frequency of the wave by the equation: 𝑣=𝑓𝜆v=fλwhere:
𝑣v is the speed of sound,
𝑓f is the frequency,
𝜆λ is the wavelength.
For a given frequency 𝑓f, if the speed of sound 𝑣v increases, the wavelength 𝜆λ must also increase to satisfy the equation. Thus, wavelength is directly proportional to the speed of sound for a given frequency. This means that in media where the speed of sound is higher, the wavelength of a sound wave of a given frequency will be longer.
Speed of Sound in Solids and Density
The speed of sound in solids is generally higher than in liquids and gases. This higher speed is primarily due to the interplay between the elasticity (or rigidity) and density of the medium.
Rigidity and Density in Solids
Rigidity (Elastic Modulus): Solids typically have much higher rigidity (measured by Young's modulus 𝐸E) compared to liquids and gases. This high rigidity means that solids can resist deformation more effectively and restore their shape quickly when deformed, allowing sound waves to travel faster.
Density (𝜌ρ): Solids usually have higher densities than liquids and gases. Although higher density alone would tend to decrease the speed of sound, the effect of the much greater rigidity in solids more than compensates for their higher density.
The speed of sound in a solid is given by: 𝑣=𝐸𝜌v=ρE
Here’s why the speed of sound is greater in solids despite their high density:
High Elastic Modulus: The elasticity (or Young's modulus 𝐸E) of solids is significantly higher than in liquids and gases. This means that the particles in a solid are strongly bound to each other and can transmit sound waves more efficiently. The restoring force in solids is much stronger, leading to a higher speed of sound.
Density Factor: While solids have higher densities, the increase in elasticity (Young's modulus) in solids is so large that it outweighs the effect of increased density. This results in a net increase in the speed of sound. The elasticity of solids increases the speed of sound more significantly than the density decreases it.
Comparison with Liquids and Gases
Liquids: Liquids have higher densities than gases but lower elastic moduli compared to solids. The speed of sound in liquids is higher than in gases primarily due to higher density and moderate elasticity.
Gases: Gases have low densities and low elastic moduli, resulting in the lowest speed of sound among the three states of matter.
Summary
Wavelength is directly proportional to the speed of sound for a given frequency. If the speed of sound increases, the wavelength increases proportionally.
Speed of sound in solids is higher despite their high density because the elasticity (rigidity) of solids is much higher than that of liquids and gases. This high rigidity more than compensates for the higher density, resulting in a greater speed of sound in solids.
Wavelength is directly proportional to the speed of sound for a given frequency. If the speed of sound increases, the wavelength increases proportionally. Speed of sound in solids is higher despite their high density because the elasticity (rigidity) of solids is much higher than that of liquids and gases. This high rigidity more than compensates for the higher density, resulting in a greater speed of sound in solids. The velocity of sound in solid is given by v=√Rρ. Throughρ is large for solids, but their coefficient of elasticity E is much larger (compared to that of liquids and gases). That is why v is maximum in case of solid. The closer the molecules are to each other and the tighter their bonds, the less time it takes for them to pass the sound to each other and the faster sound can travel. It is easier for sound waves to go through solids than through liquids because the molecules are closer together and more tightly bonded in solids.Solids are packed together tighter than liquids and gases, hence sound travels fastest in solids. The distances in liquids are shorter than in gases, but longer than in solids. The sound velocity depends on the packing arrangement of the molecules of the medium. The gases have very loosely bound molecules. On the other hand, the solids have tightly arranged molecules. The closer the molecules, the higher will be the speed of sound. Because they are so close, than can collide very quickly, i.e. it takes less time for a molecule of the solid to 'bump' into its neigh borough. Solids are packed together tighter than liquids and gases, hence sound travels fastest in solids. The distances in liquids are shorter than in gases, but longer than in solids.