Frequency = \(\frac { 1 }{ T }\)
T = 0.002
F = \(\frac { 1 }{ 0.002 }\) = 500
ie. 500 complete waves or cycles produced in one second.

1. Ultrasound is used in cleaning technology. Minute foreign particles can be removed from objects placed in a liquid bath through which ultrasound is passed.
2. Ultrasounds can also be used to detect cracks and flaws in metal blocks.
3. Ultrasonic waves are used to get images of the heart by the technique called as Echo 'cardiography'
4. Ultrasound is employed to break 'small stones' formed in the kidney into fine grains.
5. Animals such as bats and dolphins use ultrasound to navigate and communicate.
6. SONAR is a device uses ultrasonic waves to measure the distance, direction and speed of the underwater objects.

Amplitude (A):
The maximum displacement of the particles of the medium from their original undisturbed position is called amplitude.
It is denoted by A. SI unit is metre (m)
Frequency (n):
The number of vibrations produced in one second is called frequency of the wave.
It is denoted as n. SI unit is Hz or s^-1.
Time period (T):
The time required to produce one complete vibration is called time period of the wave.
It is denoted as T. SI unit is second (s).
Wavelength (A.):
The minimum distance in which a sound wave repeats itself is called its wavelength.
It is denoted by λ. SI unit is metre (m).
Velocity (v):
The distance travelled by sound wave in one second is called velocity of the sound.
It is denoted by v. SI unit is ms^-1.

1. Musical instruments such as shehnai, trumpets and Nathaswaram, Mega phones, loud speakers uses the property of reflection of sound to guide most of the sound waves from the source in the forward direction towards the audience.
2. In stethoscopes, sound produced in the body reaches doctor's ears by multiple reflection of sound that happen in the connecting tube.
3. Echo is used to find the distance between two distance objects.
4. Ultrasound is used in examing inner parts of the body and also in marine surveying.
5. Ultrasound is used in cleaning technology, to detect cracks and flaws to form the image of the heart through 'echo cardiography'.
6. Ultrasound is employed to break stones formed in the kidney.
7. 'SONAR' is a device uses ultrasonic waves to measure the distance, direction and speed of the underwater objects.
8. In Electrocardiogram (ECG) the sound variation produced by the heart is converted into electrical signals, which represents the electrical activity of the heart muscle.

V = \(\frac {2d}{t}\)
V = 1450 ms^-1
t = 4 sec
d = \(\frac {V \times t}{2}\)
d = \(\frac { 1450 \times 4}{2} \)
= 3625 m (or) 3.625 km
The distance of the submarine from the ship = 3.625 km.

Frequency of the tuning fork (n) = 540 Hz.
Velocity of sound (v) = 330 ms^-1
∴ Wavelength λ = \(\frac {v}{n}\)
= \(\frac {330}{540}\) = 0.6 m
Wavelength = 0.6 m
Time Period (T) = \(\frac { 1 }{ n }\)
= \(\frac {1}{540}\) = 0.00185
T = 0.00185 s

The audible range of average human being is in the frequency range of 20 Hz to 20000 Hz.

Sound is defined as the vibrations that travel through the air or another medium as an audible mechanical wave.
It is produced from a vibrating body (water, air etc) around it to vibrate thus producing sound.

Time period = \(\frac { t }{ Number of oscillation in time t} = \frac { 5 }{ 50 }\) = 0.1s
Frequency = \(\frac { 1 }{ Time period } = \frac { 1 }{ 0.1 } \) = 10 Hz
Frequency is 10 Hz.