SOUND WAVES

1. Sound Waves
INSTRUCTOR KASHAN FORCES ACCADEMY JHANG

3. WAVE
• A WAVE IS A DISTURBANCE IN A MEDIUM DUE TO WHICH
PARTICLES OF MEDIUM TRANSFER ENERGY FROM ONE
PLACE TO ANOTHER PLACE.
• WAVES CAN BE PRODUCED IN SOLID,LIQUID AND GASES.
• MANY WAVES REQUIRED SOME MATERIAL TO MOVE FROM
ONE PLACE TO OTHER PLACE ARE CALLED MEDIUMS.
• GASES: AIR
• LIQUIDS:WATER SOLIDS: ROPE & METAL

4. VIBRATION
• A VIBRATION IS REPEATED TO & FRO AND UP & DOWN
MOTION OF A SUBSTATNCE.
• TO & FRO MOTION OF A BODY AROUND ITS MEAN
POSITION IS CALLED VIBRATORY MOTION.
• FOR EXAMPLE:
• MOTION OF A BALL IN A BOWL
• MOTION OF PENDULUM
• MOTION OF A BODY ATTACHED TO SPRING

5. TYPES OF WAVES
• THERE ARE TWO TYPES OF WAVES.
LONGITUDINAL WAVES:
BACK AND FORTH MOVEMENT OF PARTICLES OF MEDIUM
PARALELL TO WAVE IS CALLED LONGITUDINAL WAVES
• E.G:MOTION OF SLINKY SPRING,MOTION OF
• PENDULUMN.MOTION OF SOUND WAVES.
TRANSVERSE WAVES:
UP AND DOWN MOVEMENT OF PARTICLES OF MEDIUM
PERPENDICULAR TO WAVE IS CALLED TRANSVERSE
WAVES.

6. CREST AND TROUGH(TRANSVERSE WAVES)
• THE HIGHEST PART OF TRANSVERSE WAVE IS CALLED
CREST.
• THE LOWEST PART OF TRANSVERSE WAVE IS CALLED
TROUGH. CREST
TROUGH

7. COMPRESSION AND RAREFACTION
(LONGITUDNAL WAVES)
• THE CLOSE PART OF LONGITUDINAL WAVE IS CALLED
COMPRESSION.
• THE FAR PART OF LONGITUDINAL WAVE IS CALLED
RAREFACTION.
COMPRESSION RAREFACTION

8. HOW A WAVE IS FORMED?
•A compression and a rarefaction
is combined to form a longitudinal
wave.
• What about a transverse wave?

9. WAVELENGTH
•
• A wavelength is the shortest distance between two adjacent
crests or troughs of a transverse wave.
• For longitudinal waves, it is the distance between two adjacent
compressions or rarefactions
• Wavelength is measured in metres (m).
WAVELENGTH
WAVELENGTH
WAVELENGTH
WAVELENGTH

10. AMPLITUDE
• Amplitude of a wave is the maximum distance of the particles of
the medium from the rest position.
• We can also say that it is the height of a crest or depth of a
trough (transverse wave) measured from the rest position.
• Amplitude is measured in metres (m).

11. FREQUENCY
• The number of vibrations produced by a vibrating body in one
second is called frequency
• Frequency is measured in units called hertz (Hz).
• When one wave passes through a point in one second the
frequency is 1 wave per second or 1 hertz.
• Frequency = no. of waves
time (in seconds)

12. SPEED
• The distance a wave covers in unit time called its speed.
• Speed is measured in metre per second.
• Different waves travel at different speeds.
• Sound and Light travel at different speeds.
• Light travels much faster than sound.
• Thunder is always heard after we see lightning.
• It shows that light travels much faster than sound.

13. SPEED

14. BREAKER OF SPEED OF SOUND RECORD?
• On October14, 1947, Captain Chuck Yeager of USA
became the first person to fly a plane faster than the
speed of sound.
• Fifty years later on October 15, 1997, Andy Green drove
his jet-powered car at 339 meters per second.
• His speed was faster than the speed of sound.

15. Relationship of Speed, Wavelength & Frequency
• The speed, wavelength and frequency of a wave are
related to each other by a mathematical formula.
• Speed = wavelength x frequency
• We can calculate any one of three values if we know
other two.

16. Audible Frequency Range
• The word audible means ‘able to be heard’.
• Our ears cannot hear sounds of all frequencies.
• The range of frequencies which a person can hear is
known as audible frequency range.
• A healthy human ear can hear sounds of frequencies
from about 20 Hz to 20,000 Hz.
• Different animals have different audible frequency
ranges.

17. Audible Frequency Range
 The audible frequency range
reduces in most old people.

18. PITCH
• SHRILLNESS OR GRAVENESS OF A SOUND IS
CALLED ITS PITCH.
• HIGH SHRILL SOUND IS CALLED HIGH PITCH
SOUND.
• LESS SHRILL SOUND IS CALLED LOW PITCH
SOUND.
HIGHER FREQUENCY=HIGHER PITCH

19. LOUDNESS
• A SOUND CREATED USING AN EXTRA ENERGY IS
CALLED LOUD SOUND.
LOUDNESS=AMPLITUDE

20. ULTRA & INFRA SOUNDS
• Sound waves with frequencies above the normal human
• range (20,000Hz) of hearing are called ultrasound.
• Doctors use ultrasound to examine a patient internally.
• Manufacturers of concrete slabs use ultrasound waves to
check cracks or cavities in concrete slabs.
• The sound waves which have frequencies
• below 20Hz are called infrasound.