Which quantity is determined by the stiffness and density of the medium?

Which quantity is determined by the stiffness and density of the medium?

• A. Wavelength
• B. Propagation Speed
• C. Frequency
• D. Amplitude

Answer: (B)

The speed at which ultrasound waves travel through a medium is determined by the medium’s stiffness (elastic properties) and density. A stiffer medium supports faster wave propagation because it resists compression more and can restore displacement more quickly. At the same time, higher density adds inertia, which tends to slow the wave down. The overall relationship can be thought of as c ≈ sqrt(stiffness/density). Because the speed sets how far the wave travels in a given time, it directly governs the wavelength when the frequency is fixed (λ = c/f). The frequency is determined by the transducer or source, not by the medium, and amplitude depends on energy and attenuation rather than stiffness and density. Hence, the quantity determined by the stiffness and density of the medium is the propagation speed.

The speed at which ultrasound waves travel through a medium is determined by the medium’s stiffness (elastic properties) and density. A stiffer medium supports faster wave propagation because it resists compression more and can restore displacement more quickly. At the same time, higher density adds inertia, which tends to slow the wave down. The overall relationship can be thought of as c ≈ sqrt(stiffness/density).

Because the speed sets how far the wave travels in a given time, it directly governs the wavelength when the frequency is fixed (λ = c/f). The frequency is determined by the transducer or source, not by the medium, and amplitude depends on energy and attenuation rather than stiffness and density. Hence, the quantity determined by the stiffness and density of the medium is the propagation speed.