QUIZ) ASNT L3 UT 13

241. Rough surfaces cause the echo amplitude from discontinuities with in the part to

a. increase

b. decrease

c. not change

d. change frequency

242. When a sound beam travels from a liquid Into a metal through a contoured surface the sound team

inside the metal will

a. have the phase velocities of the first symmetrical and asymmetrical modes

b. have the Phase velocity of the incident longitudinal

c. not be affected by the part geometry

d. be convergent if the surface is concave, and divergent If the surface is corvet

243. The resonant frequency of a 2 cm (0.79 in.) thick plate of Naval brass (V=4.43*105 cm/s) is

a. 0.903 MHz

b. 0.443 MHz

c. 0.222 MHz

d. 0.111 MHz

244. Resonance testing equipment generally utilizes

a. pulsed longitudinal waves

b. continuous longitudinal waves

c. pulsed shear waves

d. continuous shear waves

245. To eliminate the decrease of sensitivity close to a wall which is parallel to the beam direction

the probe used should be

a. as small as possible

b. of at low frequency as possible

c. both a and b

d. large and with a frequency as high as possible

246. Some information on the shape of a flaw may be given by

a. the shape of the echo

b. the amplitude of the echo

c. both a and b

d. neither a or b

247. Of the transducer materials listed below. the most efficient receiver is

a. quart

b. lithium sulfate

c. barium titanate

d. lead metaniobate

248. The concentration of energy In the far field of a transducer beam is

a. greatest at the outer edges of the beam

b. greatest at the center of the beam

c. the fame at the outer edges as In the center of the beam

d. directly proportional to beam width

249. In angle beam shear wave testing, skip distance will _________ as the thickness of the test specimen

is increased

a. decrease

b. not change

c. increase

d. decrease by half with double thickness

250. The thickness range of UT resonance thickness gages can be increased by

a. using large transducers

b. operating at the fundamental frequency

c. operating at a harmonic frequency

d. increasing the voltage

251. The ability of transducers to detect echoes from small defects is a definition for

a. resolution

b. sensitivity

c. definition

d. gain

252. The length of the near field for a 2.5 cm (1 In.)diameter, 5 MHz transducer placed in oil(V=1.4*105 cm/s)

is approximately

a. 0.028 cm (0.01 in)

b. 6.25 cm (2.5 in)

c. 22.3 cm (8 in)

d. 55.8 cm (22 in)

253. From the equation for the length of the near field, it can be determined that the near field can be

minimized by

a. decreasing water travel distance

b. increasing transducer diameter

c. decreasing the size of reference targets

d. decreasing test frequency

254. In a water (VL = 1.4 × 105cm/s) immersion test, ultrasonic energy is transmitted into steel(V=3.2*105cm/s)

at an incident angle of 14°, What is the refracted shear wave within the material?

a. 13°

b. 35°

c. 31°

d. 53°

255. What would be the approximate bandwidth of the transducer with the frequency response shown in

Figure 1 (-3 dB)?

a. 4MHz

b. 8 MHz

c. 10 MHz

d. 12MHz

256. The acoustic impedance for brass (V= 4.43× 105cm/s, p=8.42 gm/cm3) is

a. 0.53×105 gm/㎠

b. 1.9×105 gm/㎠

c. 9.4× 105 gm./㎠

d. 37× 105gm/㎠

257. The principal attributes that determine the differences in ultrasonic velocities among materials are

a. frequency and wavelength

b. thickness and travel time

c. elasticity and density

d. chemistry and permeability

258. What would be the wavelength of the energy in lead(V=2.1 × 105 cm/s) if it is tested with a

25 MHz transducer?

a. 119 cm (47 in.)

b. 0.525 cm (021 In.)

c. 0.0119 cm (0.005 in.)

d. 0.0084 cm (0.003 In )

259. What is the transducer half-angle beam spread of a 1.25 cm diameter, 2.25 MHz transducer in

water(V= 1.5 × 105 cm/s)?

a. 2.5°

b. 3.75°

c. 37.5°

d. 40.5°

260. The term that is used to determine the relative transmittance and reflectance of ultrasonic energy

at an interface is called

a. acoustic attenuation

b. interface refraction

c. acoustic impedance ratio

d. acoustic frequency

261. In general, when a discontinuity is thin it is a poor reflector. The maximum reflection is obtained

when the thickness of the discontinuity is equal to at least

a. 1/4 wavelength

b. 1/2 wavelength

c. 1 wavelength

d. even multiples of 1/2 wavelength

 

 

 

 

 

answer

241	242	243	244	245	246	247	248	249	250
B	D	D	B	D	C	B	B	C	C
251	252	253	254	255	256	257	258	259	260
B	D	D	C	A	D	C	D	B	C
261
A