For a 5 MHz wave, which medium yields the longest wavelength?

For a 5 MHz wave, which medium yields the longest wavelength?

• A. Fat
• B. Air
• C. Muscle
• D. Bone

Answer: (D)

Wavelength for a given frequency depends on how fast sound travels in the medium: lambda = v / f. With a fixed frequency of 5 MHz, the medium that has the highest speed of sound yields the longest wavelength. Speeds of sound approximate values: - Air about 343 m/s - Fat about 1450 m/s - Muscle about 1540 m/s - Bone about 4080 m/s Calculating the wavelengths at 5 MHz: - Bone: 4080 / 5,000,000 ≈ 0.000816 m ≈ 0.816 mm - Fat: 1450 / 5,000,000 ≈ 0.00029 m ≈ 0.29 mm - Muscle: 1540 / 5,000,000 ≈ 0.000308 m ≈ 0.308 mm - Air: 343 / 5,000,000 ≈ 6.86e-5 m ≈ 0.0686 mm Therefore, bone yields the longest wavelength.

Wavelength for a given frequency depends on how fast sound travels in the medium: lambda = v / f. With a fixed frequency of 5 MHz, the medium that has the highest speed of sound yields the longest wavelength.

Speeds of sound approximate values:

• Air about 343 m/s

• Fat about 1450 m/s

• Muscle about 1540 m/s

• Bone about 4080 m/s

Calculating the wavelengths at 5 MHz:

• Bone: 4080 / 5,000,000 ≈ 0.000816 m ≈ 0.816 mm

• Fat: 1450 / 5,000,000 ≈ 0.00029 m ≈ 0.29 mm

• Muscle: 1540 / 5,000,000 ≈ 0.000308 m ≈ 0.308 mm

• Air: 343 / 5,000,000 ≈ 6.86e-5 m ≈ 0.0686 mm

Therefore, bone yields the longest wavelength.