Physics Doppler UPDATED ACTUAL
Exam Questions and CORRECT Answers
Doppler Shift AKA - CORRECT ANSWER- ✔✔Doppler Frequency
The Doppler Effect - CORRECT ANSWER- ✔✔An apparent change in frequency as a result
of a change in wavelength caused by motion of a wave source relative to an observer
Relative motion between the sound source & the receiver creates - CORRECT ANSWER-
✔✔a frequency change
The frequency of sound changes when the sound source & the receiver - CORRECT
ANSWER- ✔✔move closer together or father apart
Amount of increase or decrease (in frequency) depends on: - CORRECT ANSWER- ✔✔-
Speed of motion
- Angle between the wave propagation direction
- Motion direction
- Frequency of wave emitted by the source
The frequency does not change when the distance between the sound source & the receiver -
CORRECT ANSWER- ✔✔remains constant
The Doppler Principle - CORRECT ANSWER- ✔✔is used to measure red blood cell
velocities
As the velocity increases, the Doppler shift - CORRECT ANSWER- ✔✔increases
If the detected frequency is *lower* than the transmitted frequency, the Doppler shift is -
CORRECT ANSWER- ✔✔negative
,If the detected frequency is *higher* than the transmitted frequency, the Doppler shift is -
CORRECT ANSWER- ✔✔positive
The Doppler shift is - CORRECT ANSWER- ✔✔a low frequency that "rides" on top of the
much higher transducer frequency
Demodulation - CORRECT ANSWER- ✔✔a process that extracts the low Doppler frequency
from the transducer's carrier frequency
Transducer frequencies of __________________ are used to perform Doppler exams -
CORRECT ANSWER- ✔✔2 MHz - 10 MHz
Doppler shifts range from _______________________ & fall into the audible range of sound
- CORRECT ANSWER- ✔✔20 Hz - 20,000 Hz (20 KHz)
Doppler Shift = - CORRECT ANSWER- ✔✔Reflected Frequency - Transmitted Frequency
Doppler shifts are created when - CORRECT ANSWER- ✔✔transmitted waves strike
moving RBCs
(+) Doppler shift occurs when blood moves _____________ the transducer - *the reflected
frequency is higher than the transmitted frequency* - CORRECT ANSWER- ✔✔towards
(-) Doppler shift occurs when blood moves __________ from the transducer - *the reflected
frequency is lower than the transmitted frequency* - CORRECT ANSWER- ✔✔away
X-axis of the Doppler spectrum represents - CORRECT ANSWER- ✔✔time
Y-axis represents the - CORRECT ANSWER- ✔✔Doppler shift or velocity
Doppler frequencies indicate _____________, not speed - CORRECT ANSWER-
✔✔velocity
, Speed - CORRECT ANSWER- ✔✔a *magnitude* & indicates the distance a RBC moves in
1 sec
Speed is reported in units of - CORRECT ANSWER- ✔✔cm/sec - any unit of distance/time
Velocity - CORRECT ANSWER- ✔✔a *magnitude* & a direction
An automobile is traveling from New York to Florida at a rate of 50 miles per hour -
CORRECT ANSWER- ✔✔- Speed = 50 miles/hour (speed is a magnitude)
- Velocity is 50 miles/hour to the south (velocity is a magnitude & a direction)
Doppler Equation - CORRECT ANSWER- ✔✔Doppler Shift = 2 x velocity of blood x
transducer frequency x cos0 / propagation speed
Doppler shift is caused by - CORRECT ANSWER- ✔✔a change of wavelength caused by
motion relative to the observer
Wavelength = - CORRECT ANSWER- ✔✔Propagation Speed / Frequency
When frequency increases, wavelength - CORRECT ANSWER- ✔✔decreases
When wavelength decreases, Doppler shift - CORRECT ANSWER- ✔✔increases
When Doppler shift increases, Transmit Frequency - CORRECT ANSWER- ✔✔increases
Propagation velocity & wavelength are ____________ related - CORRECT ANSWER-
✔✔directly
Doppler shift is ___________ related to the frequency of transmitted sound - CORRECT
ANSWER- ✔✔directly
Exam Questions and CORRECT Answers
Doppler Shift AKA - CORRECT ANSWER- ✔✔Doppler Frequency
The Doppler Effect - CORRECT ANSWER- ✔✔An apparent change in frequency as a result
of a change in wavelength caused by motion of a wave source relative to an observer
Relative motion between the sound source & the receiver creates - CORRECT ANSWER-
✔✔a frequency change
The frequency of sound changes when the sound source & the receiver - CORRECT
ANSWER- ✔✔move closer together or father apart
Amount of increase or decrease (in frequency) depends on: - CORRECT ANSWER- ✔✔-
Speed of motion
- Angle between the wave propagation direction
- Motion direction
- Frequency of wave emitted by the source
The frequency does not change when the distance between the sound source & the receiver -
CORRECT ANSWER- ✔✔remains constant
The Doppler Principle - CORRECT ANSWER- ✔✔is used to measure red blood cell
velocities
As the velocity increases, the Doppler shift - CORRECT ANSWER- ✔✔increases
If the detected frequency is *lower* than the transmitted frequency, the Doppler shift is -
CORRECT ANSWER- ✔✔negative
,If the detected frequency is *higher* than the transmitted frequency, the Doppler shift is -
CORRECT ANSWER- ✔✔positive
The Doppler shift is - CORRECT ANSWER- ✔✔a low frequency that "rides" on top of the
much higher transducer frequency
Demodulation - CORRECT ANSWER- ✔✔a process that extracts the low Doppler frequency
from the transducer's carrier frequency
Transducer frequencies of __________________ are used to perform Doppler exams -
CORRECT ANSWER- ✔✔2 MHz - 10 MHz
Doppler shifts range from _______________________ & fall into the audible range of sound
- CORRECT ANSWER- ✔✔20 Hz - 20,000 Hz (20 KHz)
Doppler Shift = - CORRECT ANSWER- ✔✔Reflected Frequency - Transmitted Frequency
Doppler shifts are created when - CORRECT ANSWER- ✔✔transmitted waves strike
moving RBCs
(+) Doppler shift occurs when blood moves _____________ the transducer - *the reflected
frequency is higher than the transmitted frequency* - CORRECT ANSWER- ✔✔towards
(-) Doppler shift occurs when blood moves __________ from the transducer - *the reflected
frequency is lower than the transmitted frequency* - CORRECT ANSWER- ✔✔away
X-axis of the Doppler spectrum represents - CORRECT ANSWER- ✔✔time
Y-axis represents the - CORRECT ANSWER- ✔✔Doppler shift or velocity
Doppler frequencies indicate _____________, not speed - CORRECT ANSWER-
✔✔velocity
, Speed - CORRECT ANSWER- ✔✔a *magnitude* & indicates the distance a RBC moves in
1 sec
Speed is reported in units of - CORRECT ANSWER- ✔✔cm/sec - any unit of distance/time
Velocity - CORRECT ANSWER- ✔✔a *magnitude* & a direction
An automobile is traveling from New York to Florida at a rate of 50 miles per hour -
CORRECT ANSWER- ✔✔- Speed = 50 miles/hour (speed is a magnitude)
- Velocity is 50 miles/hour to the south (velocity is a magnitude & a direction)
Doppler Equation - CORRECT ANSWER- ✔✔Doppler Shift = 2 x velocity of blood x
transducer frequency x cos0 / propagation speed
Doppler shift is caused by - CORRECT ANSWER- ✔✔a change of wavelength caused by
motion relative to the observer
Wavelength = - CORRECT ANSWER- ✔✔Propagation Speed / Frequency
When frequency increases, wavelength - CORRECT ANSWER- ✔✔decreases
When wavelength decreases, Doppler shift - CORRECT ANSWER- ✔✔increases
When Doppler shift increases, Transmit Frequency - CORRECT ANSWER- ✔✔increases
Propagation velocity & wavelength are ____________ related - CORRECT ANSWER-
✔✔directly
Doppler shift is ___________ related to the frequency of transmitted sound - CORRECT
ANSWER- ✔✔directly
