2. This is due to the fact that ultrasound can be transmitted through soft tissue, but is mostly reflected when it comes into contact with more dense material such as bone. This method is based on the fact that ultrasonic waves which consist of alternate compressions and rarefactions changes the density of the medium through which they pass. Similarly when ultrasonic waves enter from denser to rarer medium, then they bend toward normal. The attenuation is increased with increase in frequency of ultrasonic waves for a given medium. Sound waves of frequency more than 20,000Hz are called Ultrasonics. Sound waves with frequencies higher than the upper audible limit of human hearing are called ultrasound. The following are the main properties of ultrasonic waves: The ultrasonic waves cannot travel through vacuum. Long range detection of targets with varied surface properties. If ultrasonic waves enter from rarer medium to dense medium, then V1 < V2  so equation (5) gives sin i / sin r < 1 => i

ultrasonic waves properties 2021