What is the equation for impedance?

What is the equation for impedance?

• A. Z = Density × Propagation speed
• B. Z = Propagation speed / Density
• C. Z = Density + Propagation speed
• D. Z = Density / Propagation speed

Answer: (A)

Impedance in wave propagation is the opposition a medium offers to a passing wave. For acoustic waves, the characteristic impedance is the product of the medium’s density and the speed of the wave in that medium: Z = ρ c. This means that both a denser medium and a faster wave speed raise the impedance, which in turn influences how much of the wave is reflected at boundaries and how much is transmitted. The correct expression is density times propagation speed because it directly links the medium’s physical properties to how the wave energy is resisted and transferred. Expressions that add, divide, or invert these quantities don’t describe how the wave interacts with the medium at interfaces.

Impedance in wave propagation is the opposition a medium offers to a passing wave. For acoustic waves, the characteristic impedance is the product of the medium’s density and the speed of the wave in that medium: Z = ρ c. This means that both a denser medium and a faster wave speed raise the impedance, which in turn influences how much of the wave is reflected at boundaries and how much is transmitted. The correct expression is density times propagation speed because it directly links the medium’s physical properties to how the wave energy is resisted and transferred. Expressions that add, divide, or invert these quantities don’t describe how the wave interacts with the medium at interfaces.