Explain how defects in a metal block can be detected using ultrasound ?

Explanation

Metallic components are generally used in construction of big structures like buildings, bridges, machines and scientific equipments. The cracks or holes inside the metal blocks which are invisible from outside reduces the strength of the structure. Ultrasonic waves are allowed to pass through the metal block and detectors are used to detect the transmitted waves. If there is a defect the ultrasound gets reflected back indicating the presence of flaws or defects.