Higher frequency sound produces a beam with _____ divergence.

Higher frequency sound produces a beam with _____ divergence.

• A. Less
• B. More
• C. Equal
• D. Variable

Answer: (A)

Higher frequency sound has a shorter wavelength, and beam spread (divergence) is governed by diffraction, which depends on wavelength relative to the transducer’s size. With a smaller wavelength, the diffraction is reduced, so the ultrasound beam stays narrower as it propagates. In practical terms, the angle of beam spread is roughly proportional to wavelength divided by the aperture; as frequency increases, wavelength decreases, and the divergence decreases. This is why higher-frequency ultrasound produces a beam with less divergence. Note that increasing frequency also means greater attenuation, so penetration depth drops even though the beam is more collimated.

Higher frequency sound has a shorter wavelength, and beam spread (divergence) is governed by diffraction, which depends on wavelength relative to the transducer’s size. With a smaller wavelength, the diffraction is reduced, so the ultrasound beam stays narrower as it propagates. In practical terms, the angle of beam spread is roughly proportional to wavelength divided by the aperture; as frequency increases, wavelength decreases, and the divergence decreases. This is why higher-frequency ultrasound produces a beam with less divergence.

Note that increasing frequency also means greater attenuation, so penetration depth drops even though the beam is more collimated.