Question

label the above diagram properly and explain the process in detail ​

Answer 1

if there is a even a small defect the Ultrasonic waves get reflected back indicating the presence of the flaw defect as shown in figure.

Ultrasound reflects from a part of block which shows that thjs metal block has flaw or defect (like crack) inside it.

now,ordinary soundwave cannot be used Ford affecting the floor in metal block because they will wind around the corner of the defective location therefore enter the detector.