Question

In Sear's method, when the ultrasonic
waves are produced, the intensity of the
central image *
increases
O decreases
sometimes increases
sometimes decreases​

Answer 1

Explanation:

An ultrasonic grating is a type of diffraction grating produced by interfering ultrasonic waves in a medium altering the physical properties of the medium, and hence the refractive index, in a grid-like pattern. The term acoustic grating is a more general term that includes operation at audible frequencies.

An ultrasonic wave is a sound wave at a frequency greater than 20 kHz. The human ear cannot recognize ultrasonic waves, but animals such as bats and dogs can. Ultrasonic waves can be produced by the Piezo-electric effect and magnetostriction