Unit: waves
Year: 1993 Question#: 37
Question: The diagram below shows radar waves being emitted from a stationary police car and reflected by a moving car back to the police car.
The difference in apparent frequency between the incident and reflected waves is an example of
(1 ) constructive interference
(2 ) refraction
(3 ) the Doppler effect
(4 ) total internal reflection
What is this question really asking?
Explanation by: Diana L.
[ Return to question menu ]
Answer 1
constructive interference
INCORRECT
constructive interference is the effect produced by the interaction of 2 waves that are in phase with each other as they pass through a medium . return to top
Answer 2
refraction
INCORRECT
refraction is the bending of a wave as it enters a new medium. In this problem, the medium is just air. return to top
Answer 3
the Doppler effect
CORRECT
the Doppler effect is an apparent change in frequency and wavelength when a wave source and observer are in relative motion with respect to each other. In this case, the source is the moving car, while the observer is the police car. return to top
Answer 4
total internal reflection
INCORRECT
total internal reflection is the reflection of a ray in a denser medium from the surface of a less dense medium that occurs when the angle of incidence exceeds the critical angle. return to top
What's this question really asking?
Do you understand the Doppler effect? return to top
