SaM ~ Real World Example • Propagation of an Ultrasonic Wave in Different Materials

IMPORTANTE

• Propagating in air:IMPORTANTE
  ==We have to use frequency which are usually lower than $1\text{MHz}$.
  The reason is that with this high frequency you have a very short wavelength so a good spatial resolution along the direction of the propagation of the wave, but you you can travel with the wave for only a short length so short propagation/penetration depth.
  Therefore the most common frequencies are in the range of $\left[30\text{kHz}÷50\text{kHz}\right]$ for range measurements==.
• Similar for liquid and solid, if I want to see in depht I use a smaller frequency, otherwise If I want “clearer images” or more accuracy a higher frequency.