TradeExamPro › Welding › Nondestructive testing (Level II)
34 questions from the nondestructive testing (level ii) practice test.
10 questions, graded as you go, with the reason for every answer. No sign-up.
Which wave mode cannot travel through water or other liquids?
A. Shear wave
Shear waves need a medium with shear rigidity, and liquids and gases have essentially none, so only longitudinal waves pass through them. This is why immersion testing sends longitudinal waves through the water and produces shear waves in the part by refraction.
Reference: ASNT Level II UT study topic: wave modes
In steel, how does shear wave velocity compare with longitudinal wave velocity?
B. About half
In steel the shear velocity is about 3,230 m/s against about 5,900 m/s for longitudinal waves, roughly 55 percent. Because wavelength equals velocity divided by frequency, a shear wave at the same frequency has about half the wavelength.
Reference: ASNT Level II UT study topic: acoustic velocities
What happens when the incident angle in the wedge is increased to the second critical angle?
B. The shear wave is refracted to 90 degrees
At the second critical angle the refracted shear wave reaches 90 degrees and runs along the surface; at about this setting surface (Rayleigh) waves are generated. The longitudinal wave reached 90 degrees earlier, at the first critical angle.
Reference: Snell's law; ASNT Level II UT study topic: critical angles