Assuming the same 'Q' factor, which frequency provides the best resolving power?

Resolving power in ultrasonics is determined by the frequency of the ultrasound waves used; higher frequencies typically provide better resolving power because they produce shorter wavelengths. The resolving power is directly related to the ability to distinguish between two closely spaced reflectors.

The relationship between frequency and wavelength is inversely proportional: as frequency increases, wavelength decreases. Higher frequencies, such as 25 MHz, result in shorter wavelengths which enhance the ability to detect small flaws and differentiate between closely spaced features in a material. This principle allows for finer resolution and more detailed imaging of the internal structures of the test material.

While lower frequencies can penetrate materials more effectively, they sacrifice some of the resolution due to longer wavelengths. Therefore, among the given frequency options, 25 MHz stands out as the frequency that provides the best resolving power due to its capability to produce the smallest wavelengths.