Level 2 Flashcards
Mechanical wave motion requires
a) high pressure
b) low pressure
c) particle motion
d) ionic bonding and disbonding
C
In an homogenous and isotropic elastic medium such as low carbon steel, sound velocity a) decreases with distance from source b) varies with direction c) is constant in all directions d) depends on frequency
C
The amount of time between two compressions, or two rarefactions of an elastic wave is called a) wavelength b) period c) frequency d) velocity
B
The velocity of sound is
a) constant for all materials
b) varies with frequency
c) varies inversely with wavelength
d) is characteristic of a material
D
Compared to the atomic or molecular spacing of a material, ultrasonic wavelengths are
a) much greater
b) smaller
c) about the same distance 2
d) are multiples of the atomic spacing
A
The elastic wave that has particle motion parallel to the direction of wave propagation is called
a) longitudinal wave
b) compression wave
c) density wave
d) all of the above
D
In Rayleigh waves, particle motion is
a) parallel to the direction of wave propagation
b) right angles to the direction of wave propagation
c) retrograde
d) in counter clockwise ellipses
D
Rayleigh waves can be used in steel to penetrate up to
a) 10mm
b) 10cm
c) 1m
d) 1 wavelength
D
In bending waves (plate wave mode) particles in the middle zone of the plate vibrate
a) in longitudinal mode
b) in shear mode
c) in Rayeigh mode
d) not at all
B
In the Lamb wave called a dilational wave, particles in the middle zone of the plate vibrate
a) in longitudinal mode
b) in shear mode 3
c) in Rayleigh mode
d) not at all
A
If one sound beam passes through another moving in the opposite direction, the result will be,
a) a change in amplitude
b) a change in direction
c) a change in frequency
d) no change
A
In a standing wave, nodes and antinodes are separated by
a) 1/4 wavelength
b) 1/2 wavelength
c) 1 wavelength
d) 2 wavelengths
A
Standing waves are generated in ultrasonic testing for
a) through testing (pitch-catch)
b) resonance thickness testing
c) flaw detection
d) B-scans
B
Specific acoustic impedance is the product of
a) density and permittivity
b) hardness and velocity
c) velocity and density
d) specific activity and amplitude
C
Poisson’s ratio is expressed in units of
a) m/s
b) Pa
c) N/m24
d) no units, it is dimensionless
D
Frequency can be expressed in terms of
a) 1/s (s=seconds)
b) cps
c) Mhz
d) all of the above
D
The ratio of sound velocity in water to the longitudinal velocity of sound in steel is very nearly
a) 1:1
b) 1:2
c) 1:4
d) 1:5
C
Rayleigh wave velocities for a given material are always
a) greater than longitudinal wave velocities
b) greater than transverse wave velocities
c) less than transverse wave velocities
d) about the same as shear wave velocities
C
The ratio of the incident sound pressure to the reflected sound pressure is called the
a) acoustic impedance
b) acoustic intensity
c) coefficient of reflection
d) coefficient of transmission
C
The ratio of the incident sound pressure to the transmitted sound pressure is called the a) acoustic impedance b) acoustic intensity 5 c) coefficient of reflection d) coefficient of transmission
D
When is the coefficient of transmission a negative value?
a) if Z incident is less than Z transmitted
b) If Z incident is greater than Z transmitted
c) if Z incident equals Z transmitted
d) never
D
Incident sound pressure plus reflected sound pressure equals
a) 0
b) 1
c) transmitted sound pressure
d) none of the above
C
Total incident sound intensity can be calculated from
a) the sum of the reflected and transmitted intensities
b) the difference between reflected and transmitted intensities
c) R plus D (reflection and transmission coefficients)
d) R plus D (reflection and transmission coefficients)
A
(Sin a1) (C2) = (Sin a2) C1) is a form of
a) Krautkramer’s law
b) Snell’s law
c) Boyle’s law
d) Hooke’s law
B
If the Sine of a refracted angle is calculated to be 0.707, the refracted angle will be
a) 36 degrees
b) 45 degrees
c) 60 degrees
d) undetermined from the given information
B
For a shear wave travelling from steel to water incident on the boundary at 10 degrees will give a refracted shear wave in water with an angle of
a) 0 degrees
b) 5 degrees
c) 20 degrees
d) none of the above
D
The critical angle refers to the
a) longitudinal waves’ angle
b) incident angle
c) refracted angle
d) reflected shear wave
B
The critical angle occurs when the sine of the refracted angle equals
a) 0.707
b) 0.846
c) 1.000
d) 1.414
C
At a solid to free boundary, an obliquely incident longitudinal wave from the solid can result in, at most,
a) a reflected longitudinal wave only
b) a reflected longitudinal and reflected shear wave
c) a refracted longitudinal long wave
d) a reflected longitudinal and reflected shear and refracted longitudinal wave
B
At a liquid/solid boundary with an obliquely incident
longitudinal wave from the liquid the result could be at most be 7
a) a reflected longitudinal wave only
b) a refracted longitudinal wave only
c) a reflected longitudinal, and a refracted long wave
d) a reflected long and refracted long and shear wave
D
Given V (water) = 1.5 mm/us and V (steel) longitudinal velocity = 5.0 mm/us and shear velocity mm/us, what is the second critical angle of an incident longitudinal wave from steel.
a) 19 degrees
b) 27 degrees
c) 36 degrees
d) none of the above
D
A shear wave polarized in the plane of incidence impinging on a free boundary at right angles to the boundary will result in
a) a reflected shear wave only
b) a reflected shear wave and reflected longitudinal wave
c) reflected longitudinal wave only
d) a surface wave
A
Maximum surface wave energy is obtained when the angle of incidence is
a) 0 degrees
b) 60 degrees
c) 90 degrees
d) just over the critical angle
D
Geometric-optic treatment of ultrasonic waves fails to account for
a) reflection
b) refraction
c) diffraction
d) normal incidence
C
The relationship for acoustic pressure of spherical waves P=Pe/d, implies
a) an inverse proportionality to distance
b) infinite sound pressure at the source
c) both a and b
d) none of the above
C
Spherical and cylindrical waves reflecting off a plane surface preserve shape but not
a) velocity
b) wavelength
c) frequency
d) acoustic pressure distribution
D
The advantage of inspecting a thick solid cylinder with a waterpath two times the cylinder radius instead of just the cylinder radius is
a) increased sensitivity
b) reduced entry noise
c) smaller near zone
d) more uniform pressure through the cylinder
D
The ratio of the diameter of an oscillator to the wavelength it generates gives the
a) acoustic velocity
b) near zone length
c) acoustic impedance of the oscillator
d) number of interference maxima and minima
D
For practical purposes, the equation for the near zone distance can be approximated by (where l = wavelength and D = probe diameter)
a) D / l
b) D squared / 4 l 9
c) D squared minus l squared/4 l
d) (D-4l)/l squared
B
Given an "X-cut" normal beam contact probe on steel, the probe is 12 mm diameter and has a frequency of 2 MHz. The approximate near zone length is (V steel = 6.0mm/us) a) 4mm b) 12mm c) 24mm d) 48mm
B