WAVES (PART 6)

Question 1

1. What is the Doppler Effect?

Answer 1

• it is a well known and frequently observed
  phenomenon
• the apparent pitch of the sound is changed
• it is changed by relative motion between the sound
  source and the observer

Question 2

2. Where is the Doppler Effect used in?

Answer 2

• it is used in Diagnostic Medical procedures
• it measures the flow velocities of fluids

Question 3

3. What happens when the Source (S) is moving at a speed (vs) towards the observer?

Answer 3

• each wave peak is emitted at a distance
  (d = vsT) closer to the observer
• T = wave period

Question 4

4. What happens when the Source moves closer to the observer?

Answer 4

• the wavelength decreases
• it decreases by vsT
• it decreases from the original wavelength of λ=vT
• it does this for a sound wave travelling at a speed of V

Question 5

5. How is the new frequency observed and worked out?

Answer 5

NB:
this is a case of a moving source and a fixed observer

Question 6

6. What happens when the source is fixed and the observer is moving?

Answer 6

• there are successive peaks in the sound waves
• the time between these peaks in the sound waves will
  be decreased
• it is decreased when moving towards the source
• it is moving with a speed of vD

Question 7

7. How do we work out the new frequency?

Answer 7

• we must work out the new period
• this is shortened

NB:
this is the case for a fixed source and a moving observer

Question 8

8. What is the General case for the Doppler Effect?

Answer 8

• the two cases are combined
• they provide a general formula
• this applies to any situation where the observer and
  the source are both moving
• it also applies to any situation where the observer or
  the source are both moving

Question 9

9. What is the formula for the general case of the Doppler Effect?

Answer 9

f’ = the frequency is due to the Doppler Effect
v = the speed of the sound in the medium
vd = the speed detector
= this speed is relative to the medium
vs = the speed of the source

Question 10

10. When do we use a + sign in the equation?

Answer 10

• when there is an increase in frequency
• the source moves towards the detector

Question 11

11. When do we use a - sign in the equation?

Answer 11

• when there is an increase in frequency from the
  detector
• the source moves away from the detector

Question 12

12. Answer this question.

Answer 12

• A

Question 13

13. Answer this question.

Answer 13

• C

Question 14

14. Answer this question.

Answer 14

• answer it

Question 15

15. Answer this question.

Answer 15

• C
  (not 100% sure this is right)

Question 16

16. Answer this question.

Answer 16

• answer it

Question 17

17. Read through Summary 1.
    Does everything make sense?

Answer 17

• yes

Question 18

18. Read through Summary 2.
    Does everything make sense?

Answer 18

• yes

Question 19

19. Read through Summary 3.
    Does everything make sense?

Answer 19

• yes

Question 20

20. Read through summary 4.
    Does everything make sense?

Answer 20

• yes

Question 21

21. Read through summary 5.
    Does everything make sense?

Answer 21

• yes

Question 22

22. Read through summary 6.
    Does everything make sense?

Answer 22

• yes

Question 23

23. Read through summary 7.
    Does everything make sense?

Answer 23

• yes

Question 24

24. Read through summary 8.
    Does everything make sense?

Answer 24

• yes