The physics seminar covered the range of human hearing and applications of ultrasound. It discussed how the normal human hearing range is 20 Hz to 20 kHz, but children and some animals can hear higher frequencies. It then covered several medical and industrial uses of ultrasound, including ultrasonic cleaning, humidification, welding, and medical applications like detecting flaws, destroying kidney stones and cataracts, and ultrasound imaging of fetuses.

1. Physics seminar
The topic of our seminar is :the sound
A . Range of hearing
B . Uses of ultrasound

2. Range of hearing
Range of hearing
The audible range of human being to hear is from 20 Hz to 20000 Hz .children under the
age of five and
some animals can hear up to 25 kHz
Older people cannot hear properly
And range below 20 Hz are called infra sonic sound
Rhinos communicate using 5 Hz of noise
Frequencies higher than 25 kHz is called ultra sonic sound

3. Application of ultra sound
 Ultrasonic cleaning
 Ultrasonic cleaners, sometimes mistakenly called supersonic cleaners, are used at
frequencies from 20 to 40 kHz for jewelry, lenses and other optical parts, watches,
dental instruments, surgical instruments, diving regulators and industrial parts.
 An ultrasonic cleaner works mostly by energy released from the collapse of millions
of microscopic cavitation's near the dirty surface.
 The bubbles made by cavitation collapse forming tiny jets directed at the surface .
 Ultrasonic disintegration
 Similar to ultrasonic cleaning, biological cells including bacteria can be
disintegrated. High power ultrasound produces cavitation that facilitates particle
disintegration or reactions.
 This has uses in biological science for analytical or chemical purposes
(sonication and sonoporation) and in killing bacteria in sewage.

4.  High power ultrasound can disintegrate corn slurry and enhance liquefaction and
saccharification for higher ethanol yield in dry corn milling plants.
 Ultrasonic humidifier
 The ultrasonic humidifier, one type of nebulizer (a device that creates a very fine
spray), is a popular type of humidifier. It works by vibrating a metal plate at
ultrasonic frequencies to nebulize (sometimes incorrectly called "atomize") the
water. Because the water is not heated for evaporation, it produces a cool mist. The
ultrasonic pressure waves nebulize not only the water but also materials in the
water including calcium, other minerals, viruses, fungi, bacteria, and other
impurities. Illness caused by impurities that reside in a humidifier's reservoir fall
under the heading of "Humidifier Fever".
 Ultrasonic humidifiers are frequently used in aeroponics, where they are generally
referred to as foggers.
 Ultra sonic welding
 In ultrasonic welding of plastics, high frequency (15 kHz to 40 kHz ) low
amplitude vibration is used to create heat by way of friction between the materials
to be joined.

5.  The interface of the two parts is specially designed to concentrate the energy for the
maximum weld strength.

6.  It can be used to detect
 flaws in the objects such as buildings ,blocks,iron and etc
 It is used in medicine for many purposes
 A
 The destroying of kidney stones
 B
 They can destroy cataract
 C
 We can see the baby inside mothers womb .without x- ray using ultra sonic
waves which wont affect the fetus

7. The end