MP Board · Class 9 · Science · SoundExplain the application of ultrasonic sound in detecting flaws and cracks in metal blocks.

Ultrasonic waves are widely used in quality control to detect invisible cracks and flaws inside metal blocks used in big structures like bridges and buildings. Ultrasound waves are passed through the metal block, and detectors are placed on the opposite side to receive the transmitted waves. If there is a crack or flaw, the ultrasonic beam gets reflected back from that defect and cannot pass through, indicating the presence of a structural defect.