Ppt prepared by Dr. F Jeyamangalam

1. Dr.F.JEYAMANGALAM
Head & Associate Professor of Physics
Sarah Tucker College [Autonomous]
Tirunelveli - 627007
23-08-2022
PROPERTIES OF SOUND AND DOPPLER EFFECT

2. Types of wave
Characteristics & Properties
Speed of Sound wave
Phenomenon exhibited
Doppler Effect

6. the waves travel.

11. Point.

13. PROPERTIES OF SOUND WAVES

14. Low frequency sound waves = low pitch
High frequency sound waves = high pitch
When things vibrate slowly they make a low sound.
When things vibrate quickly they make a high pitched sound.

15. • When a longer piano string vibrates, it vibrates
more slowly and creates a low pitch.
• When a shorter piano string vibrates, it
vibrates faster and creates a higher pitch.
Listen to different pitches:

17. Normal

18. is produced.

24. It refers to the multiple reflections or echoes in a
certain medium
REVERBERATION

26. INTERFERENCE OF SOUND
Sound waves can interfere in two ways- destructively
and constructively. The intensity of the sound is
increased when there is constructive interference; This
takes place when the sound waves arrive at the same
time and are in phase.
The intensity of the sound is reduced when there is
destructive interference; This happens when waves
arrive at intervals and are out of phase.

28. RESONANCE OF SOUND

31. DOPPLER EFFECT
Named after
Christian Doppler
(Austrian) 1803-1853

33. The Doppler Effect is a change in pitch…due
to a change in frequency
DOPPLER EFFECT

34. DOPPLER EFFECT - DEMOSTRATION
Imagine a bug jiggling
its legs and bobbing up
and down in the middle
of a quiet puddle
What would happen to
the waves if the bug
began to swim forward,
toward B?
In front of the bug…the frequency ↑
Behind the bug…the frequency ↓

35. SOUND AND THE DOPPLER EFFECT
The Doppler effect causes the
changing pitch of a siren
In front of the car… the pitch ↑
Behind the car… the pitch ↓

36. An animation illustrating how the Doppler effect causes a car engine or siren
to sound higher in pitch when it is approaching than when it is receding. The
red circles represent sound waves.
Change of wavelength caused by motion of the source.
DOPPLER EFFECT

37. LIMITATIONS OF DOPPLER EFFECT
● Doppler Effect is applicable only when the velocities of the
source of the sound and the observer are much less than the
velocity of sound.
● The motion of both source and the observer should be along the
same straight line.
● The medium at rest.

39. DOPPLER EFFECT AND RADAR
Police use the Doppler effect of
radar waves to measure the speeds
of cars on the highway

40. Doppler RADAR

42. ❖ It can be described as the apparent change in the
frequency of the light observed by the observer due to
relative motion between the source of light and the
observer.
❖ When the light source moves away from the observer,
the frequency received by the observer will be less
than the frequency transmitted by the source. This
causes a shift towards the red end of the visible light
spectrum. Astronomers call it the redshift.
❖ When the light source moves towards the observer,
the frequency received by the observer will be greater
than the frequency transmitted by the source. This
causes a shift towards the high-frequency end of the
visible light spectrum. Astronomers call it the blue
shift.
DOPPLER EFFECT IN LIGHT

43. DOPPLER EFFECT IN ASTRONOMY

44. APPLICATION OF DOPPLER EFFECT
1. It is used in astronomical measurements
2. Radar and modern navigation
3. Studying the motion of the stars
4. Finds its application in Robotics
5. Used in dynamic real-time path planning in sports –
Robo Soccer
6. Used in radar to measure the velocity of detected
objects
7. Echocardiogram
8. Weather forecasting

45. ❖ Types of wave
❖ Characteristics and Properties
❖ Speed of Sound wave
❖ Phenomenon – Reflection, Refraction,
Interference and Diffraction
❖ Doppler Effect
❖ Application of Doppler Effect