The document discusses characteristics of waves and sound communication. It covers topics like: - Sound is produced by vibration and travels through a medium as a wave. - A wave has properties like amplitude, wavelength, frequency and time period. - Sound waves are longitudinal waves that transfer energy through variations in pressure. - Communication systems like microphones, speakers, telephones and satellites convert sound to electrical signals and vice versa to allow long-distance communication. - Other uses of waves discussed include sonar, radar and ham radio communication.

1. SOUND AND
COMMUNICATION

2. CHARACTERISTICS OF WAVE
➔ Sound is a result of vibration. The vibration is produced by a source, travels in the medium of as a
wave and is ultimately sensed through eardrum.
➔ A medium is must for a mechanical wave like sound to travel. (electromagnetic waves need no
medium to travel like waves from distant stars and artificial satellites in space.)
➔ A wave involves a periodic motion, movement that repeats itself.
➔ Crest (raised part) and trough (low part) are essential components of a wave.
➔ A wave transfers energy from one point to other without the movement of medium particles from
one point to other.
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3. Representing a wave
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4. Representing a wave
A wave is represented by its wavelength, amplitude, frequency and time period.
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5. Representing a wave
➔ Amplitude: maximum height of the wave.
➔ Wavelength: distance between adjacent trough or adjacent crest. It’s represented by roman letter 𝞴
(lambda).
➔ Time period: the time taken by a wave to pass a given point or time takes to complete one oscillation.
It’s measured in seconds (s).
➔ Frequency: the number of oscillation that completes in one second. It’s measured in Hertz (Hz )
When the frequency rises, the time period falls, and when the frequency falls, the time period
rises.
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6. Speed or Velocity
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● Speed is scalar quantity and velocity is a vector quantity.
● Unit of Speed and Velocity are m/s
○ Scalar quantity is a physical quantity with magnitude or size like weight. (How much)
It’s based on distance covered in a specific time.
○ Vector quantity is a physical quantity that has both magnitudes and directions like
force. (How much and which direction). It’s based on displacement occurred in a
specific time.

7. Distance and Displacement
▹ The complete length of the path between any two points is called
distance.
▹ Displacement is the direct length between any two points when
measured along the minimum path between them.
▹ To calculate distance, the direction is not considered.
▹ To calculate displacement, the direction is taken into consideration.
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8. Speed or Velocity
▹ T= 1/n (‘n’ is frequency)
▹ velocity= frequency x wavelength
Or V= n x 𝞴
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9. Waves
▹ Waves that produces the sense of sound for human being are called
sound waves or audible waves.
▹ Only frequencies lying between 16 Hz to 20,000 Hz are audible to human
beings.
▹ Sounds below 16 Hz are called infrasonic waves.
▹ Sounds above 20,000 Hz are called ultrasonic waves.
▸ Bats use audible for seeing in the dark. It can produce ultrasonic
waves.
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10. Movement of sound in air
▹ Sound waves travel in fluid and solids as longitudinal waves.
▸ the medium or the channel moves in the same direction with
respect to the wave.
▸ In a transverse wave the medium or the channel moves
perpendicular to the direction of the wave.
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11. ▹ The particles of medium oscillate in the
direction of the wave movement.
▹ It’s made of rarefactions and
compressions.
Longitudinal and Transverse waves
● The particles of medium oscillate in
the direction perpendicular to the
wave movement
● It’s made of crests and troughs
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13. ➔ A compression is a region in a longitudinal wave where the particles are closest together.
➔ A rarefaction is a region in a longitudinal wave where the particles are farthest apart.
Compression and rarefaction
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15. Types of Waves
▹ Mechanical waves: waves that require medium for travelling.
▸ Its speed is dependent on the properties of medium such as inertial and elastic
properties.
▹ Electromagnetic (em) waves: waves that results from acceleration of charge and does not
require medium for travelling.
▸ It travels through vacuum. It has two fields. Electric field and magnetic field and both are
perpendicular to other.
▸ Examples of electromagnetic waves: Radio, microwaves, Infrared, Visible, Ultraviolet, X-
rays, Gamma Rays.
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16. Velocity of sound in different materials.
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Medium Velocity
Steel 5200 m/s
Water 1520 m/s
Air 330 m/s
Glass 4540 m/s
Silver 3650 m/s

17. Types of Waves
▹ Mechanical waves can be either transverse or longitudinal while
electromagnetic wave is only transverse.
▹ Wavelength of transverse wave : distance between adjacent trough or adjacent
crest.
▹ Wavelength of longitudinal wave: distance between adjacent Compression and
adjacent Rarefaction.
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18. Nature, Measure and Quality of Sound
▹ Sound level is measured in units of decibel (dB)
▹ ‘deci ‘ means one-tenth and Bel named after inventor of telephone Alexander
Graham Bell.
▹ For average human ears, the whisper is about 30 dB, Normal conversation is
about 65 dB, a jet plane taking off makes a noise of 150 dB. Beyond 85 dB
sound is damaging and can lead to temporary loss of hearing. Noise raises
blood pressure and causes anxiety.
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19. Nature, Measure and Quality of Sound
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20. Nature, Measure and Quality of Sound
▹ Decibel meter measures with the help of a special crystal called Piezoelectric
crystals .
▹ Music is a set of sound that is pleasing to hear and is not random.
▹ Noise is random and irritates.
▹ We evaluate a sound with its quality, pitch and loudness.
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21. Uses of different kind of Waves: Sonar
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▹ SONAR is stands for SOund NAvigation and Ranging.
▹ It works on principle of echo of transmitted sound waves from objects.
▹ Use: electromagnetic waves lose energy fast in ocean because water
conducting electricity. But sonar waves can travel farther in water.

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▹ Two types of SONAR: Passive and Active.
▹ We use Passive Sonar to detect sound waves that are present around.
(Leonardo da Vinci dipped pipes in water to detect ships, Detection of
movements of ships and submarines during WWII )
▹ Active SONAR is very important and it has two major components.
▸ A transmitter consisting of a signal generator, power and transducer
▸ A detector.
Uses of different kind of Waves: SONAR

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▹ Two types of SONAR: Passive and Active.
▹ We use Passive Sonar to detect sound waves that are present around. (Leonardo da Vinci
dipped pipes in water to detect ships, Detection of movements of ships and submarines during
WWII )
▹ Active SONAR is very important and it has two major components.
▸ A transmitter consisting of a signal generator, power and transducer
▸ A detector.
▹ The signal is sent as a narrow beam. Otherwise the reflections will be coming from many sides.
Uses of different kind of Waves: SONAR

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Uses of different kind of Waves: SONAR

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▹ Theoretically, the distance travelled by a wave is twice the distance between
transmitter and target to be detected. So if the velocity of sound in water is v
and t is time-lapse between transmission and detection.
d = ½ x v x t
Uses of different kind of Waves: SONAR

26. Uses of different kind of Waves: Radar
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▹ RADAR stands for RAdio Detection And Ranging.
Uses:-
● Observation of atmospheric objects and phenomena like clouds,
cyclones, rain, prediction of weather (Doppler weather radar).
● Air Traffic Control (ATCR)
● Ship navigation (Marine Radar)
● Military use

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28. Uses of different kind of Waves: Radar
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▹ RADAR is radio wave equivalent of SONAR. In a RADAR, a radio wave does the
same job as sound wave in SONAR.
▹ Basic elements of RADAR system are:
▸ Pulse Generator Transmitter
▸ Object
▸ A receiver with an antenna

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30. Uses of different kind of Waves: Radar
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▹ Transmitter: it generates and sends a radio wave. The waves are
electromagnetic and travels at the velocity of light. So the reflection time is
very low. It sends and receives waves in no seconds so it’s called pulsed
transmitter.
▹ Doppler effect: the change in wave frequency during the relative motion
between a wave source and its observer. Such Radars called Doppler RADAR

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NEED AND IMPORTANCE OF
COMMUNICATION

32. Types of Communication systems and Devices
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▹ Microphone and speakers
▹ Telephone
▹ Satellite, Computer and internet
▹ HAM (amateur radio)

33. Microphone and Speakers
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▹ A Microphone converts sound into electrical entity (Voltage). It consists a
diaphragm which converts sound into voltage using possible transducers.
▹ The speaker converts Voltage into Sound by moving the diaphragm of speaker
and producing vibrations in air.
▹ Condenser microphone: it has thin diaphragm and it’s very sensitive.

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35. Microphone and Speakers
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▹ Ribbon microphone:

36. Telephone
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▹ Alexander Graham Bell
▹ Types: Handset, Mobile phone, Satellite Phone, Internet phone
▹ Function is to allow two way communication.
▹ Wired and unwired phones:
▸ In wired phone it has microphone which receives voice and converts to
electric signal, and a speaker.

37. Telephone
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▹ Major parts of telephone:
▸ Cradle with a hook switch.
▸ Mouth piece
▸ Hearing piece.
▹ The signal as electrical current sent to a junction box using copper or aluminium wires.
▹ This waves converted exchanged to microwaves and sends to satellites for international
calls.

38. Telephone
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▹ In mobile phones the principle is same, but the sound is converted as electromagnetic wave
through space via antennas, towers, switching stations etc..
▹ When a number is dialed the electromagnetic field is spread all around. The signal is received
by nearby microwave tower and then by switching station. Then the station re-transmit it in
all directions and a part is available to the other antennas in other places. when an antenna
near the intended receiver gets the signal it also get transmits it and that this is received by
the antenna of the intended mobile which rings.

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40. Satellites
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▹ Bodies that revolve around planets called satellites.
▹ All planets in our Solar system except Mercury have natural satellites.
▹ Moon is natural satellite of Earth.
▹ First artificial satellite was Sputnik- I launched by USSR in 4 October, 1957
▹ India’s first artificial satellite was Aryabhatta in 1975.
▹ Bhaskara-I, Bhaskara-II, Apple, INSAT, are series of artificial satellites used for
communication, TV and radio broadcasts.

41. Satellites
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▹ The artificial satellites plays key role in country’s infrastructure.
▹ The geostationary orbits (GEO) is also called Clarke Orbit.
▹ Medium Earth Orbits
▹ Low Earth Orbits

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43. Types of Satellites
TYPE CODE Min KMs Max KMs
Low Earth Orbit LEO 160 1400
Medium Earth Orbit MEO 10 15,000
Geostationary Earth Orbit GEO - 36,000
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45. Computer and Internet
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▹ Very common and it plays a major role in our daily life such as money transactions,
▹ Emails

46. HAM
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▹ The term coined taking first letters from surnames of S Hyman, Bob Alby and Poogie Murray.
▹ They started an Ameteur Radio Club in 1908
▹ It uses radio waves in wavelength of 10 cm to 10 km.
▹ Sound is converted into electromagnetic signal and transmitted using an antenna and the
receiver converts it back to sound.

47. THANKS!
Any questions?
You can find me at @hafizabid
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