Which of the following frequencies will produce the shortest wavelength?

The frequency and wavelength of a wave are inversely related, as described by the formula:

[ \text{Wavelength} (\lambda) = \frac{v}{f} ]

where ( v ) is the speed of sound in the material (which is constant for a given medium) and ( f ) is the frequency.

In this relationship, as the frequency increases, the wavelength decreases. Therefore, among the frequencies provided, the highest frequency will yield the shortest wavelength.

Since 25 MHz is the highest frequency listed, it will produce the shortest wavelength when compared to the other choices of 1 MHz, 10 MHz, and 5 MHz. Therefore, selecting 25 MHz as the answer accurately reflects this principle of wave behavior in nondestructive testing applications.