Question

Ultrasonic waves produced by a vibrating quartz crystal are;
A. Only longitudinal
B. Only transverse
C. Both longitudinal and transverse
D. Neither longitudinal nor transverse

Answer 1

Hint: There are two types of wave, electromagnetic and mechanical. Mechanical waves have two types: longitudinal and transverse waves. Properties of ultrasonic waves tend to be similar to longitudinal waves. The ultrasonic frequency has a high frequency.

Complete step by step solution:
To produce ultrasonic waves there are mainly two important methods, based on two different phenomena, namely piezoelectric effect and magnetostatic effect.
We know that under the piezoelectric oscillator method, piezoelectric crystals such as quartz are used to produce ultrasonic waves.
We know that quartz crystal naturally exists in a hexagonal prism shape with a pyramid attached on both ends. The line joining the endpoints of the pyramids is called the optical axis. The plane perpendicular to this optical axis has two axes, one is electric or X-axis and the other is mechanical or Y-axis. So in a vibrating quartz crystal, only longitudinal ultrasonic waves are produced.
The wave in which particles of the medium vibrate in a direction parallel to the direction of propagation of waves is called longitudinal waves. Example - Waves produced on elastic spring are longitudinal waves. Longitudinal waves divide the medium bingo alternate compressions (region particles are crowded) and refraction (region particles well separated).
All medium particles along the path of the wave vibrate with the same period and frequency. Each wave consists of one and one compression and one rarefaction. The distance between the consecutive (successive) compressions (rarefaction) is known as wavelength. Longitudinal waves can propagate through solids, liquids and gases.
There is a change in pressure and density of medium during propagation. Longitudinal waves can travel through a medium having an elasticity of volume (i.e. Solid, liquid, gas). Every particle of the medium does not perform S.H.M. with the same period and frequency.
These waves cannot be polarized. The velocity of longitudinal waves (sound) is given by $v=\sqrt{\dfrac{E}{\rho }}$where E - elasticity of medium and ρ- density of the medium. The speed of longitudinal in solid in the form of the long rod is given by $v=\sqrt{\dfrac{Y}{\rho }}$where Y- Young's modulus of the material of rod and ρ - density of solid.

Note: There is a change in pressure and density of medium during propagation. Longitudinal waves can travel through a medium having elasticity of volume (i.e. Solid, liquid, gas). Every particle of the medium does not perform S.H.M. with the same period and frequency.
These waves cannot be polarized. The velocity of longitudinal waves (sound) is given by $v=\sqrt{\dfrac{E}{\rho }}$where E - elasticity of medium and ρ- density of medium. The speed of longitudinal in solid in the form of long rod is given by $v=\sqrt{\dfrac{Y}{\rho }}$where Y- Young's modulus of material of rod and ρ - density of solid.