ULTRASONIC TESTING | ESL INDUSTRIAL SUPPORT SERVICES | QUESTION BANK

ULTRASONIC TESTING

QUESTION BANK

ULTRASONIC TESTING:

• Ultrasonic testing uses high frequency sound energy to conduct examinations and make measurements.
• Ultrasonic examinations can be conducted on a wide variety of material forms including castings, forgings, welds, and composites.
• A considerable amount of information about the part being examined can be collected, such as the presence of discontinuities, part or coating thickness; and acoustical properties can often be correlated to certain properties of the material.

1.The displacement of particles from its mean position is called

1. Mean free path
2. Cycle
3. Wave length
4. Vibration

2.Ultrasonic waves pass through

1. Solids
2. Liquids
3. Gases
4. a, b & c
5. Solids, liquids, gases except vacuum.

3.If wave length is increased, the frequency will

1. Increase
2. decrease
3. Remains the same
4. None of the above
5. All the above.

4.Calculate the frequency for a wave length of 1.5 mm at a velocity of 6.1 km/sec.

1. 3 MHZ
2. 4 MHZ
3. 5 MHZ
4. 4 MHZ

5.Longitudinal waves are the ones in which the particle motion is

1. Perpendicular to the direction of propagation
2. In the same direction of propagation
3. Elliptical in the direction of prorogation
4. Is dispersive.

6.The wave which travels through solids, liquids and gases is

1. Longitudinal wave
2. Surface wave
3. Shear wave
4. Plate waves

7.The transverse waves do not propagate through liquids and gases because

1. Liquids and gases don’t posses modules of elasticity
2. The alteration between actions or modules is small
3. Either (a) or (b)
4. None of the above

8.Lamb waves are used to inspect

1. Bar stock
2. forging
3. Thick plates
4. Thin sheets

9.The general law that explains wave behavior at the interface is called

1. Einstein’s theory
2. Huygens’s principle
3. Newton’s Law
4. Snell’s Law

10.Second critical angle is the angle of incidence at the interface of the dissimilar materials when

1. Mode converted longitudinal wave angle becomes 90°
2. Refracted, mode converted transverse wave angle becomes 90° resulting of which surface wave is generated at the plane of boundary
3. Mode converted longitudinal wave is eliminated from the second medium
4. (b) or (c)

11.Surface wave is generated at the boundary of Perspex and steel, at

1. First critical angle
2. The incidence angle of 40°
3. Second critical angle
4. Both a & b

12.Bending of sound waves at the tip or edge of a discontinuity is

1. reflection
2. refraction
3. Interference
4. diffraction
5. c & d

13.The zone where the defect size can not be estimated exactly due to interference of wave fronts is

1. Far field
2. Fresnel zone
3. Near Field
4. (b) or (c)

14.The sound intensity in far zone decrease with the

1. Distance of its travel
2. length of refracted wave length
3. Distance of travel and also across the beam
4. both (b) and (c)

15.When frequency and dia of a crystal is decreased, the beam spread would be

1. decreased
2. increased
3. No change
4. either (a) or (b)

16.Beam divergence is a function of the diameter of the crystal and the wave length of the beam transmitted through a medium and it

1. Increases if the frequency or crystal diameter is increased
2. Decreases if the frequency or crystal diameter is decreased
3. Increases if the frequency is increased and crystal diameter is decreased
4. Decreases if the frequency is decreased and the crystal diameter is decreased
5. None

17.A search unit that contains three or more individual transducer elements is known as

1. Dual transducer
2. Probe
3. Mosaic transducer
4. None of the above

18.Scattering of an ultrasonic wave occurs due to

1. Homogeneous condition
2. Non – homogeneous condition of materials like grain boundaries and minute non – metallic inclusions
3. Diffraction
4. Refraction

19.A-Scan equipment displays a data presentation which is related to

1. Plan view of the area under inspection.
2. Cross sectional view
3. Elapsed time & elapsed time, from left to right and signal amplitude

20.The control which is taking care of frequency amplitude and the pulse repetition rate is

1. Pulse length
2. Amplifier
3. Pulsar
4. Receiver

21.Both the delay and range controls are

1. In pulsar unit
2. Rejection control
3. Part of sweep generator
4. None

22.In ultrasonic testing, the time duration of the transmitted pulse is referred to as

1. the pulse amplitude
2. pulse length or width
3. the pulse shape
4. None of the above.

23.An ultrasonic testing instrument that displays pulses representing the magnitude of reflected ultrasound as a function of time or depth of metal is said to contain

1. continuous display
2. `A’ scan presentation
3. `B’ scan presentation
4. `C’ scan presentation

24.The pulse repetition rate for thicker materials and thinner materials?

1. Same
2. lower
3. higher
4. higher for thinner and lower for thicker material

25.The echoes should always be read from

1. Trailing part touching base line
2. Height of the peak
3. Foot of the leading echo

26.The crystal which can be used at elevated temperature is

1. Lithium sulphate
2. Polarized ceramics
3. Quartz x-cut
4. Both a & b

27.The Curie point or critical temperature is defined as

1. The temperature at which the vibration of crystal suddenly falls to 50%.
2. The temperature at which the vibration of crystal suddenly falls to 0%
3. The temperature at which the crystal loses its piezo electric properties
4. a & b

28.The efficiency of a transducer is described as

1. Sensitivity
2. Resolution, efficiency
3. Sensitivity, resolution & energy conversion
4. a & b & c

29.When using two separate search units, one a transmitter and another as receiver, the most efficiency combination is

1. Quartz transmitter Lithium Sulphate as receiver
2. Lithium Sulphate transmitter, Quartz as receiver
3. Barium Titanate as transmitter and Lithium Sulphate as receiver
4. Lithium Sulphate as transmitter and Barium Titanate as receiver.

30.The testing technique in which the crystal or transducer is parallel to the test surface and ultrasonic waves enter the material being tested in a direction perpendicular to the test surface is

1. Angle beam
2. Normal beam
3. straight beam
4. b or c
5. surface beam

31.The advantages of using dual probe is

1. Dead zone is eliminated
2. The best of transmitters and receivers could be used as option
3. We can use any range of frequency
4. both a & b

32.By using immersion testing,

1. Gross defects are noted
2. Sensitivity is reduced
3. Near surface resolution is achieved
4. None of the above

33.The reason for attaching lenses to the transducer in immersion testing is

1. to enhance sensitivity
2. to reduce resolution
3. to enhance resolution
4. both a & c,
5. both a & b

34.Line of focus is achieved in

1. Spherical lens
2. cylindrical lens
3. Round lens
4. point lens

35.With the aid of cylindrical lens, we will be able to achieve

1. Line focus
2. Point focus
3. both a & b
4. None

36.By using delay tip units, we are able to eliminate.

1. Resolving power
2. Sensitivity
3. both a & b
4. Dead zone

37.When using focused transducers non-symmetry in a propagation sound beam may be caused by

1. Backing materials vibrations
2. Porosity in lenses
3. Lens centering or misalignment
4. All of the above.

38.Which of the following test system has the best near resolution of the same frequencies?

1. Straight beam probe with rubber membrane
2. Straight beam probe with perspex delay
3. Straight beam probe without protecting membrane
4. Straight beam probe with low pulse strength

39.The efficiency to resolve two discontinues at different depths would be improved by

1. Decreasing the frequency
2. Shortening the pulse duration
3. Increasing the amplitude
4. None

40.The resolving power for frequency 4 MHZ compared to 2 MHZ is

1. Same
2. Worse
3. Better
4. None