Q130 / 270 · NDA 2017 (Phase 2) · General Ability

Which one of the following statements is not correct?

A
Ultrasonic waves cannot get reflected, refracted or absorbed.
B
Ultrasonic waves are used to detect the presence of defects like cracks, porosity, etc. in the internal structure of common structure materials.
C
Ultrasonic waves can be used for making holes in very hard materials like diamond.
Correct answer
D
Ultrasonic waves cannot travel through vacuum.

Solution

Ultrasonic waves cannot get reflected, refracted or absorbed, Ultrasonic waves are used to detect the presence of defects like cracks, porosity, etc. in the internal structure of common structure materials, Ultrasonic waves can be used for making holes in very hard materials like diamond.

Hence, the correct answer is option: 'D'.

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