All Flashcards
What is the effect of an approaching source on the observed frequency?
The observed frequency is higher than the rest frequency (positive Doppler shift).
What is the effect of a receding source on the observed frequency?
The observed frequency is lower than the rest frequency (negative Doppler shift).
What effect does increasing the relative velocity between the source and observer have?
A larger difference between the observed and rest frequencies.
What is the effect if the source and observer move at the same velocity?
There is no Doppler shift, and the observed frequency equals the rest frequency.
What is the effect of a positive Doppler shift?
The source is approaching the observer.
What is the effect of a negative Doppler shift?
The source is receding from the observer.
What is the difference between observed frequency when a source approaches versus recedes?
Approaches: Observed frequency is higher. | Recedes: Observed frequency is lower.
Compare positive and negative Doppler shift.
Positive: Observed frequency > rest frequency (approaching). | Negative: Observed frequency < rest frequency (receding).
Compare the use of Doppler effect in astronomy vs. medical ultrasound.
Astronomy: Measures motion of stars/galaxies. | Medical Ultrasound: Detects blood flow velocities.
Compare the wavelength when the source is approaching versus receding.
Approaching: Wavelength is compressed. | Receding: Wavelength is stretched.
Compare the pitch of ambulance siren when approaching versus receding.
Approaching: Higher pitch. | Receding: Lower pitch.
Define the Doppler effect.
The change in frequency of a wave in relation to an observer who is moving relative to the wave source.
What is 'rest frequency'?
The frequency of a wave when the source and observer are not moving relative to each other.
Define 'observed frequency'.
The frequency detected by the observer, which differs from the rest frequency when there's relative motion.
What does 'redshift' indicate in astronomy?
Redshift (lower frequency) indicates objects moving away from the observer.
What does 'blueshift' indicate in astronomy?
Blueshift (higher frequency) indicates objects moving toward the observer.