Explain with the help of a diagram,how defects in a metal block can be detected using ultrasound.

(N/A) Ultrasound can be used to detect cracks and flaws in metal blocks. Metallic components are generally used in the construction of large structures like buildings,bridges,machines,and scientific equipment.
Cracks or holes inside metal blocks,which are invisible from the outside,reduce the structural strength of the component.
To detect these,ultrasonic waves are passed through the metal block,and detectors are placed on the opposite side to receive the transmitted waves.
If there is even a small defect or flaw,the ultrasound waves encounter the boundary of the defect and get reflected back,indicating the presence of the flaw,as shown in the diagram.