Generally, ultrasonic waves do not pass through thick iron plates. Iron is a dense, highly attenuating material, meaning it absorbs and reflects a significant amount of ultrasonic energy.

Here's why:

* High frequency: Ultrasonic waves with high frequencies (above 20 kHz) have shorter wavelengths. These waves interact more strongly with the material's microstructure (crystal lattice, grain boundaries), leading to significant reflection and absorption.

* Density: Iron's high density contributes to its attenuation of ultrasonic waves. The wave's energy is lost due to friction and scattering within the material.

* Thickness: A 1cm thick iron plate is a substantial barrier for ultrasonic waves. The thicker the material, the more attenuation occurs.

However, there are some exceptions:

* Lower frequency: Ultrasonic waves with very low frequencies (below 20 kHz) can penetrate a few millimeters into iron.

* Specific applications: Some specialized ultrasonic techniques, such as pulse-echo methods, can measure the thickness of iron plates even if they are quite thick. These techniques use the reflected waves to determine the material's properties.

In summary:

While it's unlikely that a typical ultrasonic wave will pass through a 1cm thick iron plate, it's not entirely impossible. The specific frequency and application will determine the outcome.