Which statement describes the relationship between bandwidth and resolving power?

• A. Bandwidth does not affect resolving power
• B. Bandwidth reduces resolving power
• C. Resolving power is inversely proportional to bandwidth
• D. Increasing bandwidth improves resolving power

Answer: (D)

Bandwidth is about the range of frequencies a pulse contains. A wider bandwidth makes the emitted ultrasonic pulse shorter in time, which reduces the spatial pulse length. Since axial resolving power—the ability to distinguish two reflectors along the beam path—depends on how short that pulse is, a shorter spatial pulse length lets you separate echoes from closely spaced features more easily. So, increasing bandwidth directly improves resolving power in the axial direction. Note that lateral resolving power depends more on beam width and aperture, not bandwidth, so the bandwidth mainly affects axial resolution. The other statements contradict this relationship by saying bandwidth has no effect, lowers resolving power, or is inversely related; none fit the way broader bandwidth sharpens the ability to resolve separate echoes.