Question

State two properties of ultrasound that make it useful to us.

Answer 1

Hint: Define vibration. Define the frequency and amplitude of vibration. Obtain the types of vibration depending on their frequency range. The ultrasound has a frequency greater than 20000 Hz. Find out how we can use different types of vibration depending on the properties due to their frequencies and wavelengths.

Complete step-by-step answer:
 Vibration can be defined as a phenomenon where an object oscillates about an equilibrium position. The vibration can be a regular vibration such as the motion of a pendulum or it can be an irregular one.
Sound wave are formed when a vibrating object make its surrounding medium vibrate
Amplitude of a vibration can be given as the maximum distance the object covers in either side of the equilibrium position.
Frequency of a vibration is given by the number of vibrations occurring per second. It can be explained as a vibrating object is in to and fro motion. A complete vibration occurs when an object moves from one extreme position to the other and again moves back to the first extreme position. The number of complete cycles that occurs in a second is called frequency of the vibration. Unit of frequency is Hz(hertz). One hertz is equal to one complete cycle per second.
Now, sound waves with frequency greater than 20000 Hz are called ultrasound.
Ultrasound has a high frequency and very small wavelength. The energy of ultrasound is very high since its frequency is high.
The ultrasound can travel along a well-defined straight path.it does not bend appreciably at the edges of an obstacle because of its small wavelength
Uses of ultrasound-
We use ultrasound in sonar to measure the depth of see. The sonar releases an ultrasound which is reflected at the bottom of the sea and then it can detect the reflected ultrasound. By measuring the time interval, we can get the depth of the sea.
Ultrasound can be used to see if there is any defect in crystals or metals. If we transfer ultrasound in a material if there is some defect or impurity in the material the ultrasound will deflect and we get a returning signal.

Note: Vibration of frequency above 20,000 Hz is called ultrasound. Vibration of frequency below 20 Hz is called infrasound. We cannot hear ultrasound also. Human ears are capable of hearing frequencies between 20 Hz and 20,000 Hz. This frequency range is called audible range.