Quiz On Physics GK Question And Answers

1. What component of a transducer changes electrical to mechanical and mechanical back to electrical engergy?

PZT

Transducer

2. Put in decreasing order of propagation speed.

Gas, liquid and solid

Solid liquid and gas

Liquid gas solid

3. Put in decreasing order

Deca, deci, centi, micro

Deci, deca, centi, micro

Micro, centi, deca, deci

Centi, micro, deci, deca

4. If the frequency of US is increased from 0.77 MHz to 1.54 MHz, what happends to the wavelength?

Doubles

Halved

Remain the same

4 times greater

5. Which transducer would be best to image superficial structures?

Small diameter, high frequency

Small diameter, low frequency

Large diameter, high frequency

Large diameter, low frequency

6. What is the production of deformation from voltage called?

Piezoelectricity

Impedance

Cogeneration

Flux

7. The frequency closest to the lower limit of US is

19,000 kHz

10,000 MHz

20,000 msec

15,000 Hz

8. How many cm are 60 millimeters

600

6

0.6

0.006

60 mm = 60.0 mm move decimal to the left one unit so 60.0 mm = 6 cm

Explanation

60 mm = 60.0 mm move decimal to the left one unit so 60.0 mm = 6 cm

9. With good images on the CRT but not on the strip chart recorder, one should

Increase the gain

Check the scan head

Check the same converter

Adjust the recorder

10. The most likely amount of reflection at a boundary between soft tissue is:

1%

22%

34%

99%

11. If the output of an US machine is calibrated in dB and the output is increased by 20 dB, the beam intensity is increased

100 times

1,000,000 times

20 times

10 times

12. Put in increasing order of propagation speed

Air bone water

Bone water air

Air water bone

Water air bone

Bone air water

13. Compression is used to

Decrease the amplitude

Decrease the range of amplitudes

Decrease the range of frequencies

14. What is the actual time that an US machine is creating a pulse?

Duty factor

Period

Pulse period

Pulse duration

15. If a 5MHz sound wave is traveling in the tissues listed below, which will have the longest wavelength?

Fat

Air

Muscle

Bone

The speed of sound in bone is the highest 3500 m/s. Solid travels fastest in solids, slower in liquids and slowest in gas. speed m/s = frequency Hz x wavelength m

Explanation

The speed of sound in bone is the highest 3500 m/s. Solid travels fastest in solids, slower in liquids and slowest in gas. speed m/s = frequency Hz x wavelength m

16. Which of the following will result in the greatest number of shades of grapy in a digital image display?

Large pixels with many bits/pixel

Small pixels with few bits/pixel

Many TV lines per frame

High contrast

Narrow dynamic range

17. The impedances of tissue is 3 x 10^5 rayls and for the PZT crystal is 6 x 10^6 rayls. What is the best impedance for the matching layer?

36 x 10^5

3,600

10,000

9.5 x 10 ^5

9 x 10^4

18. What is propagation speed determined by

Wavelength

Intensity and density

Amplitude

Density and elasticity

Density and amplitude

19. What is the minimum value of the duty factor?

10.0

1%

1.0

0.0%

20. In which of these biologic tissues will sound waves propagate most quickly?

Tendon

Blood

Lung

Fat

Amniotic fluid

21. What is displayed on the y-axis of an m-mode image?

Time

Time of flight

Echo intensity

Red blood cell velocity

22. What is the elimination of voltages that do not exceed a certain level?

Amplification

Decompensation

Reject

Demodulation

23. If the frame rate increases and the lines per frame is unchanged, what else must happen?

US speed increases

Frequency increases

Depth increases

Depth decreases

24. All of the following statements regarding in-vitro bioeffects are true EXCEPT?

In vitro bioeffects conclusions are clinically relevant

In vitro bioeffects are always real

In vitro bioeffects are vey important

In vitro bioeffects may not be applicable to clinical settings

25. How many data bits are needed to represent 46 gray shades?

46

5

6

8

26. As the impedances (z (rayls) = density (kg/m^3) x prop. speed (m/s) or acoustic resistance to sound traveling in a medium, becomes vastly different, the

Reflection increases

Transmission increases

Refraction increases

Absorption increases

27. Under which of the following conditions is lateral resolution improved?

Decreased beam diameter

Decreased pulse duration

Decreased imaging depth

Decreased pixel size

Decreased spatial pulse length

28. Which of the following is associated with cavitation?

Thermal index

Snell's Law

Avagadro's Number

Mechanical index

29. All of the following will improve temporal resolution EXCEPT

Increased line density

Single rather than multi focus

Higher frame rate

Shallower depth of view

Slower speed of sound in a medium

30. If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happend to the power?

Quadrupled

Doubled

Halved

Unchanged

31. How is range ambiguity artifact eliminated?

Lower the PRF

Raise the PRF

Increase the gain

Use a lower frequency transducer

32. Under which circumstances is cavitation most likely to occur

High frequency and low power

High intensity and high frequency

Low intensity and low frequency

Low frequency and high signal amplitude

33. What is the maximum velocity limit for a 3 MHz CW Doppler unit operating at a depth of 4cm?

40 cm/s

200 cm/s

2.5 m/s

4 m/s

None of the above

CW Doppler does not have an imposed maximum velocity limit like PW Doppler. In fact, CW Doppler may be used in instances where accurate velocities cannot be obtained with PW Doppler

Explanation

CW Doppler does not have an imposed maximum velocity limit like PW Doppler. In fact, CW Doppler may be used in instances where accurate velocities cannot be obtained with PW Doppler

34. What is the significance of gray scale variation in the spectrum of a pulssed wave Doppler display?

It represents the number of red blood cells creating the reflection

It represents the velocity of red blood cells

It represents the speed of red blood cells

It represents the convergence of red blood cell lamina

It determines the enseble length

35. All of the following are true of normal cavitation EXCEPT:

Harmful bioeffects are commonly observed

It is also known as inertial cavitation

Only a 10% increase in pressure is needed to convert to this from stable cavitation

Temperatures in the thousands of degreesare created

It is consistent with shock waves

36. TRUE OR FALSE
A system which was working well now does not display clear images in the far field. This may be a problem with the monitor.

True

False

37. Which of the following is determined by the source and the medium?

Frequency

Period

Propagation speed

Range resolution

38. A commonly used process for determining direction in a Doppler instrument is

Zero crossing detection

Autocorrelation

Phase quadrature detection

Range gating

Spectral analysis

39. What method is used to steer the color beam with a linear array transducer?

Mechanical

Electronic time delays

Electronic voltage variation

Apodization

The color beam cannot be steered with a linear array transducer

40. With normal incidence, what factors affect refraction of US?

Propagation speeds

Frequencies

Attenuation coefficients

None of the above

41. An amplifier of an ultrasound system increases the voltage of a signal from 0.0001 to 0.1 volt. What is the amplification

60 dB

30 dB

1,000 dB

90 dB

42. What are typical clinical Doppler frequencies

1 - 10,000 Hz

1 - 10 MHz

2 - 1,000 kHz

40 - 45 kHz

43. As a result of _____________ the propagation sped increases

Increasing stiffness and increasing density

Increasing stiffness and increasing elasticity

Decreasing compressibility and decreasing density

Decreasing stiffness and decreasing density

44. If 300,000 cycles occur in a second, what is the wave's frequency?

3 MHz

30 kHz

300 MHz

3 kHz

0.3 MHz

45. Increasing the wall filter during Doppler sampling will:

Increase visibility of low velocity signals

Increase spectral broadening

Decrease bandwidth

Reduce display of low frequency shifts

Reduce aliasing

46. What would be the most likely result from increasing the transmit frequecy of the color Doppler?

Improve sensitivity to slow flow

Improved penetration for imaging flow in deep tissues

Reduced flash artifact obscuring small vessel flow

Reduced color Doppler aliasing

Improve visibility of complex flow hemodynamics

47. The packet size in color Doppler refers to the number of :

Pulses per second

Sample volumes per scan line

Scan lines per unit area

Pulse - listen cycles per acoustic scan line

Pulses required to create one frame

48. Which of the following improves signal to noise ratio

Dynamic range

Frame averaging

Gray scale

Edge enhancement

Receiver gain