A parallel beam of ultrasound is incident normally on the surface of a layer of fat of thickness 
, as shown in the figure below.
For the ultrasound, 
is the intensity just after entering the surface of the fat layer, 
is the intensity incident on the fat-muscle boundary, 
is the intensity reflected from the fat-muscle boundary, and 
is the intensity received back. Some data for the fat are given in the table below.
Calculate the time interval between a short pulse of ultrasound initially entering the layer of fat and then returning back to the surface of the fat layer.
Calculate the ratio 
.
Intensity is 
of intensity . Determine the ratio 
.
The specific acoustic impedance of the muscle is greater than that of the fat. State the effect, if any, on the value of the ratio of an increase in the difference between the specific acoustic impedance of the muscle and that of the fat.
.
.
