Increasing the frequency on a multifrequency transducer from 3.5 MHz to 5.0 MHz will:

Increasing the frequency on a multifrequency transducer from 3.5 MHz to 5.0 MHz will:

• A. Increase the sound propagation speed
• B. Increase the pulse length
• C. Increase penetration
• D. Decrease the wavelength

Answer: (D)

The essential idea is that wavelength in tissue is inversely related to frequency: λ = c / f, where c is the speed of sound in tissue (about 1540 m/s) and is essentially constant for a given medium. Increasing the frequency from 3.5 MHz to 5.0 MHz makes the wavelength shorter because the same sound speed is now spread over a higher frequency. The wavelength shrinks by the ratio 3.5 / 5 ≈ 0.7, so it’s about 30% shorter. The propagation speed doesn't change with frequency, so that option isn’t correct. Higher frequency also tends to reduce penetration due to greater attenuation, so penetration depth would not increase. Pulse length depends on the number of cycles and the wavelength; with a higher frequency, the wavelength is shorter, so the pulse length does not increase and typically would decrease or stay the same for a given pulse structure. Thus, the effect that aligns with the change is the decrease in wavelength.

The essential idea is that wavelength in tissue is inversely related to frequency: λ = c / f, where c is the speed of sound in tissue (about 1540 m/s) and is essentially constant for a given medium. Increasing the frequency from 3.5 MHz to 5.0 MHz makes the wavelength shorter because the same sound speed is now spread over a higher frequency. The wavelength shrinks by the ratio 3.5 / 5 ≈ 0.7, so it’s about 30% shorter.

The propagation speed doesn't change with frequency, so that option isn’t correct. Higher frequency also tends to reduce penetration due to greater attenuation, so penetration depth would not increase. Pulse length depends on the number of cycles and the wavelength; with a higher frequency, the wavelength is shorter, so the pulse length does not increase and typically would decrease or stay the same for a given pulse structure. Thus, the effect that aligns with the change is the decrease in wavelength.