Question

Which method is suitable for producing ultrasonic waves of frequency 10MHz?​

Answer 1

Answer:

Piezoelectricity is suitable method for producing ultrasonic waves of frequency 10MHz.

Answer 2

Sound beam frequencies

Most ultrasonic testing is available within 400 kHz to 25 MHz. These vibrations are beyond the audible range and propagate in the test material as waves of particle vibrations. Sound beams of all frequencies can penetrate fine-grained material without difficulty. When using high frequencies in coarse-grained material, interpretation becomes difficult as interference in the form of scattering is noted. Depth of penetration is better achieved by lower frequencies.

The selection of a specific frequency for testing is mainly dependent on the material's property and goal of the testing.

Frequencies up to 1 MHz are generally a good choice, and they have better penetration, less attenuation, and scatter less by coarse grains and rough surfaces. The disadvantage of low frequencies is that they have a large angle of divergence and, as such, they can’t resolve small flaws.

On the other side, the high-frequency transducers emit more concentrated beams with better resolving power, but they are more scattered by coarse grains and rough surfaces.

Frequencies above 10 MHz are normally not used in contact testing, because the higher-frequency transducers are thinner and fragile. As the frequency of sound vibrations increase, the wavelength correspondingly decreases and approaches the dimension of the molecular or atomic structure. In an immersion testing, however, all frequencies can be used because there is no physical contact between the transducer and the material being tested.