Question

Ultrasound has a frequency of vibration

• A. between $20$ and $20000\text{Hz}$
• B. below $20\text{Hz}$
• C. above $20000\text{Hz}$
• D. between $500$ and $10000\text{Hz}$

Answer 1

The correct option is C

above $20000\text{Hz}$

Ultrasonic wave:

1. It is a longitudinal wave.
2. When an electrical signal generator provides a pulse of electrical energy to a piezoelectric crystal in a transducer, the crystal vibrates, converting the electrical pulses into mechanical vibrations then ultrasonic waves are produced.
3. The inaudible sound having frequency is more than $\text{20 kHz}$ is termed as Ultrasonic wave.

Diagram of ultrasonic wave is shown as follows:

Hence, option (C) is the correct answer.