The document discusses the Doppler effect, which is the apparent change in frequency of sound or other waves due to relative motion between the source and observer. It provides examples of how the frequency is higher when the source is moving toward the observer and lower when moving away. Applications of the Doppler effect include radar, which uses changes in radio wave frequency to detect objects' speed and distance, and sonar, which works similarly but uses sound waves underwater for navigation and detection.

1. DOPPLER EFFECT

2. DOPPLER EFFECT
1. Definition
2. Explanation with four cases
3. Applications

3. DOPPLER EFFECT
• Definition
“The apparent change in
frequency of sound due to the
relative motion between the source
and the observer”.

4. Resting sound source
source
at rest
observer
at rest
Frequency fs Frequency fo
s o
f f

V=340m/s

5. Sound source moving toward observer
source observer
at rest
Frequency fs
Frequency fo
o s
f f

Observer hears
increased pitch
(shorter wave length)

6. Sound source moving away from observer
source
observer
at rest
Frequency fs
Frequency fo
o s
f f

Observer hears
decreased pitch
(longer wave length)

8. Observer moving away from source
Observer in motion
source
at rest
Obser moves away from source)
o s
f f


9. Observer moving towards source
Observer in motion
source
at rest
Obser moves towards source)
o s
f f


10. APPLICATION OF DOPPLER EFFECT
• RADAR
(Radio Detection And
Ranging) is a way to
detect and study far off
targets by transmitting a
radio pulse in the
direction of the target
and observing the
reflection of the wave.
• It’s basically radio echo

11. RADAR
RAdio Detection And Ranging
Radar observables:
• Target range
• Target angles (azimuth & elevation)
• Target size (radar cross section)
• Target speed (Doppler)
• Target features (imaging)
Antenna
Transmitted
Pulse
Target
Cross
Section
Propagation
Reflected
Pulse
(“echo”)

12. SONAR
So sound
Na navigation and
R ranging
• A sensor is used to detect objects
through the use of high or low
frequency sound waves.