1. The Doppler Effect
May 20, 2013

2. Objectives
1. Identify the Doppler effect
2. Explain its cause and uses
3. Understand the terms and cause of
Sonic Boom

3. Doppler Effect
 Fire Engine
 Car Horn
 Change in
frequency due to
the motion of the
vibrating object

4.  The Doppler Effect

5. Sound Waves
1. As an object moves toward
you, frequency seems shorter
– higher pitch
2. As an object moves away,
frequency seems longer –
lower pitch
3. Never the speed that changes,
just the frequency

6.  The Doppler Effect

7. Uses of the Doppler Effect
 Doppler Radar
 Police Radar

8. Wave Barrier and Bow Waves
 When the source is moving as fast as
the waves it produces it reaches a wave
barrier
 Once it passes its wave speed is
creates a V shaped pattern – Bow Wave

9. Shock Waves and Sonic
Booms
 Shock Waves – Form overlapping cones that
Form a V
 Sonic Boom – sharp crack heard when
supersonic aircraft’s shock waves pass

11.  The Sonic Boom
 Doppler Demo's

12. Light Waves
1. Red shift –
frequency is lower
therefore red light
is seen
2. Blue shift –
frequency is higher
therefore blue light
is seen

14. The Stars
 Scientists use this knowledge to
measure the speed of rotation of the
stars
 And the distance of galaxies