UT cw 3

WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY

Ultrasonic Testing Coursework 3 Answer all questions. 1. The time required to perform one complete cycle is called the: a) b) c) d)

Period Frequency Wavelenght Velocity

2. Ultrasonic vibrations are generally defined as having a frequency above: a) b) c) d)

5,000 cps 20,000 cps 100,000 cps 1,000,000 cps

3. Wavelenght is defined as: a) The distance a wave travel to the back surface of the specimen b) The distance a wave form advanced while a particle makes on complete vibration or orbit c) The number of cycles produced per second d) The time required for a wave to reach a certain point in the specimen. 4. A definite relationship exists among the three factors, velocity, frequency and wavelength. This relationship is expressed by the formula. a) b) c) d)

F=λxV V=λ / F F=V/λ λ=V-F

5. Acoustic impedance is defined as a) b) c) d)

The product of material density and a wave velocity The ratio of material density to wave velocity The ratio of wave velocity to sound density The product of wave velocity and frequency

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WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY 6. The purpose of couplant is to: a) b) c) d)

Filter undesirable reflections from the specimen Tune transducer to the correct operating frequency Reduce attenuation within the specimen Transmit ultrasonic wave from the transducer to the specimen

7. A couplant can be a) b) c) d)

Water Oil A plastic material All of the above

8. The formula expressing the angle of refraction of a sound beam passing from one material to another a) Sin a = Velocity a Sin b Velocity b b) Sin a x Velocity b = Velocity a Sin b c) Sin a x Velocity a = Velocity b Sin b d) Both A and B are correct 9. The angle of reflection of an ultrasonic beam is: a) b) c) d)

Equal to the angle of incidence Approximately four times the angle of incidence Approximately half the angle of the incidence Equal to the angle of refraction

10. Longitudinal (compression) waves produce vibrations which are a) b) c) d)

In the same direction as the motion of the sound. Perpendicular to the motion of the sound. Elliptical Symmetrical.

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WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY 11. Shear or transverse waves are described as having a) Particle motion normal (90) to direction of propagation and a velocity Approximately half that of longitudinal waves b) Exceptionally high sensitivity due to low attenuation resulting from longer wavelengths when propagating through water c) A velocity approximately twice that of surface waves in the direction of propagation d) Particle motion perpendicular (90) to direction of propagation and no attenuation in water 12. Ultrasonic waves transmitted in fluids such as water are usually: a) b) c) d)

Lamb waves Rayleigh waves Shear waves Longitudinal waves

13. When the angle of incidence for a longitudinal wave exceeds the critical angle: a) b) c) d)

Longitudinal wave mode will be at its maximum amplitude in the specimen Longitudinal wave mode will be totally reflected Shear wave mode will be totally reflected Longitudinal wave mode will be transmitted into the specimen

14. The amount of beam divergence from a quartz crystal is primarily dependent on: a) b) c) d)

Type of test Tightness of crystal backing in the search unit Frequency and crystal size Pulse lenght

15. The Perspex insert in the IIW block is equivalent to what thickness in steel? a) b) c) d)

100 mm 50 mm 25 mm 23 mm

16. Transducers used in the majority of ultrasonic inspections exhibit which effect? a) b) c) d)

Magnetostrictive Piezoelectric Electromechanical Thermomagnetic

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WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY 17. The zone in an ultrasonic beam where fluctuations in sound intensity exist is referred to: a) b) c) d)

Dead zone Near field Far field Beam axis

18. If frequency is increased wavelength will: a) b) c) d)

Increase Decrease Remain the same but velocity increases Remain the same but velocity decreases

19. The principle of ultrasonic resonance is commonly used for? a) b) c) d)

Locating large discontinuities Locating porosity Measuring wall thickness None of the above

20. The primary purpose of reference blocks : a) b) c) d)

To aid the operator in obtaining maximum back reflection To obtain the greatest sensitivity possible from an instrument To obtain a common reproducible reference standard None of the above

21. The piezoelectric material in the probe: a) b) c) d)

Converts electrical energy to mechanical energy Converts mechanical energy to electrical energy Both A and B Neither A nor B

22. The gradual loss of energy as ultrasonic vibrations travel through a material is referred to: a) b) c) d)

Reflection Refraction Reproducibility Attenuation

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WORLD CENTRE FOR MATERIALS JOINING TECHNOLOGY 23. A general term applied to all cracks, inclusion, blow holes etc. which cause a reflection of ultrasonic energy is? a) b) c) d)

A dispenser A discontinuity An attenuator A refractor

24. In what type of ultrasonic inspection are waves transmitted into the test material the form of repetitive shock vibrations: a) b) c) d)

Pulse-echo testing Continuous testing Resonance testing None of the above

25. The angle formed by an ultrasonic wave as it enters a medium of different characteristics than the one from which it came and a line drawn perpendicular to the interface between the two media is called: a) b) c) d)

The angle of incidence The angle of refraction The angle of rarefaction The angle of reflection

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