Which one of the following statements is not correct ........

General Science (NDA) Physics

Which one of the following statements is not correct?

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.

Ultrasonic waves cannot travel through vacuum.

Explanation:

Ultrasonic waves can get reflected, refracted or absorbed.

The statement ‘ultrasonic waves cannot get reflected, refracted or absorbed’ is not correct as bats navigate in dark with the help of reflection of ultrasonic wave.

The ultrasonic waves are reflected and refracted just like light waves. i.e. (a) Angle of incidence is equal to angle of reflection. (b) Incident ray, reflected ray and normal lie in same plane.