A beam of ultrasound is incident normally at a boundary between two tissues, X X\,X and YYY. The physical properties of the tissues are shown in the table below:
| Tissue XXX | Tissue YYY | |
|---|---|---|
| Density of tissue | ρ\rhoρ | 1.4ρ1.4\rho1.4ρ |
| Speed of ultrasound | vvv | 1.5v1.5v1.5v |
What percentage of the intensity of the ultrasound is reflected at the boundary?
1.3%
5.8%
12.6%
35.5%