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Flashcards in Physics Final Deck (134)
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1

T/F Macro means bigger and micro means smaller

True

2

T/F The symbol for millions is mega and millionths is micro

True

3

T/F The symbol for hundreds is giga and the symbol for hundredths is hecto

False; hundreds is hecto (h), hundredths is centi (c)

4

T/F A wave with a frequency of 15,000 MHz is ultrasonic

True

5

T/F If the power of a wave is halved, the intensity is reduced to one-fourth its original value

False; intensity is the power of a beam divided by its cross-sectional area. If we halve the power, we will halve the intensity

6

T/F If the amplitude of a wave is increased to 3 times its original value, the intensity is increased by 6 times

False; Intensity is proportional to the amplitude squared. If we triple the amplitude, we increase the intensity by a factor of nine.

7

T/F Propagation speed is determined by the medium

True

8

T/F Propagation speed increases as frequency increases

False; they are unrelated

9

T/F We need one intensity to calculate decibels

False; we need two intensities to calculate decibels

10

T/F As the path length increases, attenuation of US in soft tissue increases

True

11

T/F Spatial peak intensity is always lower than the spatial average intensity

False; Spatial peak intensity is always higher than the spatial average intensity

12

T/F In addition to location within the beam, sound wave intensities also vary over time

True

13

T/F SPTA intensity is the most relevant intensity with respect to tissue heating

True

14

T/F The duty factor is a unit less number with a value between 0 and 1

True

15

T/F There are two different methods to measure and report intensities

False; there are 6 different methods to measure and report intensities

16

T/F The duty factor for a pulsed ultrasound system is 2%.

False; with anatomic imaging the duty factor is 0.2%

17

T/F An ultrasound beam has the same intensity at different depths or at different side to side locations within the beam

False; the beam will have different intensities

18

T/F At a particular depth, the center of a sound beam is more intense than the edges

True

19

T/F Temporal peak intensity is maximum in time

True

20

How many hertz is 3MHz?

3,000,000 Hz

21

How much bigger is a billion than a million?

1,000

22

What are the units of wavelength?

unit of length, mm or m

23

What are the units of frequency?

Hertz; Hz

24

What are the units of intensity?

W/cm^2

25

What are the units of propagation speed?

units: m/s, mm/ μs, or any distance divided by time

26

What are the units of period?

units of time, microseconds, seconds, hours, or days

27

Of the following which grouping is determined by the sound source?

Amplitude, power, intensity
Period, frequency

28

If the intensity remains the same while the power is doubled, what happens to the beam area?

Doubles

29

A sound beam travels a total of 10cm in 2 seconds. What is the speed of the sound in this medium?

5cm/sec

30

What term describes the time from the start of a pulse to the end of that pulse?

Pulse duration