Which of the following effects can be used to produce ultrasonic waves?
Answer: Option A
When an alternating magnetic field is applied to a ferromagnetic material, then the rod is thrown into vibrations, thereby producing ultrasonic waves at resonance. Therefore ultrasonic waves can be produced using magnetostriction effect.
What is the principle for measurement of the velocity of ultrasonic waves?
Answer: Option B
When ultrasonic waves are passed through a liquid, due to variation in pressure, the liquid will act as diffraction grating called acoustical grating. Under this condition when a monochromatic light is passed through the acoustical grating, the light gets diffracted. By using this velocity can be determined.