Which of the following properties is proportional to the pulse repetition frequency?

1. Spatial is a term used to describe:

 

a. time

b. speed

c. space

d. distance

2. Which of the following units measures the attenu­ation of sound in soft tissue?

a. ms

b. dB

c. rayls

d. dB/cm

3. If the frequency is increased, pulse duration will:

a. double

b. increase

c. decrease

d. remain unchanged

4. Which of the following metric prefixes denotes 1 billion?

a. deca

b. mega

c. tetra

d. giga

5. Which of the following units of measurement repre­sents the number of pulses occurring in 1 second?

a. ms

b. kHz

c. mW

d. W/cm2

6. Which of the following formulas determines the impedance of a medium?

a. attenuation multiplied by the propagation speed of the medium

b. propagation speed of the medium multiplied by the round-trip time

c. density of the medium multiplied by the attenuation coefficient

d. density of the medium multiplied by the propagation speed of the medium

7. Weakening of a sound wave as it travels through a medium defines:

a. scattering

b. harmonics

c. attenuation

d. acoustic impedance

8. Which of the following occurs when a sound wave strikes a large, smooth surface at a 90° angle?

a. refraction

b. specular reflection

c. Rayleigh’s scatter

d. nonspecular reflection

9. With perpendicular incidence, what percentage of the incident beam continues to the next medium?

a. 50%

b. 85%

c. 99%

d. 100%

10. The unit of measurement used to describe the amplitude of a pressure wave is:

a. rayl

b. watt

c. joule

d. variable

11. Which of the following properties is proportional to the pulse repetition frequency?

a. period

b. duty factor

c. penetration depth

d. spatial pulse length

12. Which of the following will most likely decrease the propagation speed of a wave?

a. increasing the penetration depth

b. increasing the stiffness of the medium

c. decreasing the transducer frequency

d. increasing the density of the medium

13. For short pulses, the quality (Q) factor is equal to:

a. the distance of one pulse

b. one half of the frequency

c. the number of cycles in a pulse

d. the intensity of the sound beam

14. The positive half of a pressure wave corre­sponds to:

a. amplitude

b. intensity

c. rarefaction

d. compression

find the cost of your paper

Sketch the load characteristics, terminal voltage/load current, of the following types of DC generator

1. (a) Sketch the load characteristics, terminal voltage/load current, of the following types of DC generator: (i) series-connected, (ii) shunt-connected and (iii) compound-connected.   (b) State one purpose for which….

what happens if the resistance in series with the shunt field of a DC motor is increased in value

1. Sparking at the trailing edges of the brushes in a DC machine is usually prevented by fitting   (a) copper gauze brushes (b) a compensating winding (c) a compound….

Calculate the synchronous speed of a 10-pole three-phase machine connected to a 50 Hz supply.

1. The generator characteristic shown in Figure 9.28 is for a   (a) shunt machine (b) series machine (c) differentially compounded machine (d) cumulatively compounded machine 2.The speed of a….