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ASNT NDT III UT study materials
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ASNT NDT III UT practice questions

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Question 1Ultrasonic Testing (UT) Method Fundamentals and Principles

In ultrasonic testing, the property that describes the maximum variation in acoustic pressure within a wave cycle is called the:

  1. Velocity
  2. Wavelength
  3. Amplitude Correct answer.
  4. Frequency

Explanation

Amplitude is the magnitude of the pressure disturbance from its equilibrium value and determines the echo height displayed on the instrument. Frequency, wavelength, and velocity describe the periodic and propagation characteristics rather than the magnitude of the disturbance.

Question 2Ultrasonic Testing (UT) Method Fundamentals and Principles

The acoustic impedance of a material is the product of its density and its:

  1. Sound velocity Correct answer.
  2. Elastic modulus
  3. Attenuation coefficient
  4. Poisson ratio

Explanation

Acoustic impedance equals density multiplied by sound velocity, and it governs how much energy is reflected at an interface. The other listed quantities describe elastic or attenuation behavior but are not part of the impedance definition.

Question 3Ultrasonic Testing (UT) Method Fundamentals and Principles

When a longitudinal wave strikes a boundary at normal incidence between two media, the reflected energy is greatest when the difference in acoustic impedance between the media is:

  1. Zero
  2. Small
  3. Large Correct answer.
  4. Negative

Explanation

The reflection coefficient depends on the impedance mismatch; the larger the difference, the greater the fraction of energy reflected. Small or zero mismatch transmits most of the energy, and impedance is a positive quantity.

Question 4Ultrasonic Testing (UT) Method Fundamentals and Principles

Which wave mode can propagate through a liquid?

  1. Longitudinal Correct answer.
  2. Lamb
  3. Shear
  4. Rayleigh surface

Explanation

Liquids support bulk compressional motion but not shear stress, so only longitudinal waves propagate in them. Shear, Rayleigh, and Lamb waves all require shear elasticity and therefore need a solid medium.

Question 5Ultrasonic Testing (UT) Method Fundamentals and Principles

The piezoelectric element in a typical ultrasonic transducer converts electrical energy into:

  1. Light
  2. Magnetic flux
  3. Mechanical vibration Correct answer.
  4. Thermal energy

Explanation

The piezoelectric effect is bidirectional: applying a voltage strains the crystal, producing mechanical vibration that launches sound into the part. The reverse effect converts returning echoes back into voltage.

Question 6Ultrasonic Testing (UT) Method Fundamentals and Principles

A transducer's near field (Fresnel zone) length in a solid depends primarily on the crystal diameter, the wavelength, and the:

  1. Frequency and velocity through wavelength Correct answer.
  2. Pulse repetition rate
  3. Attenuation coefficient
  4. Beam divergence angle

Explanation

Near field length is approximately D squared divided by four times wavelength, so it depends on diameter and wavelength, with wavelength set by velocity and frequency. Attenuation, PRF, and divergence do not define the near field boundary.

Question 7Ultrasonic Testing (UT) Method Fundamentals and Principles

The angle at which a refracted shear wave travels at 90 degrees to the interface normal, beyond which no refracted shear wave exists, is called the:

  1. Angle of incidence
  2. Second critical angle Correct answer.
  3. First critical angle
  4. Snell angle

Explanation

At the first critical angle the refracted longitudinal wave reaches 90 degrees; at the second critical angle the refracted shear wave also reaches 90 degrees, leaving only a surface wave. Angles of incidence and Snell angles are general terms, not these specific thresholds.

Question 8Ultrasonic Testing (UT) Method Fundamentals and Principles

In a pulse-echo instrument, the horizontal sweep that represents time or distance is called the:

  1. Reject control
  2. Gate
  3. Gain control
  4. Time base Correct answer.

Explanation

The time base (sweep) maps elapsed time to displayed horizontal position, calibrated in distance for a given material. Gain, reject, and gates modify amplitude or select signal regions but do not define the horizontal scale.

Question 9Ultrasonic Testing (UT) Method Fundamentals and Principles

Which couplant is generally preferred for rough or vertically oriented surfaces?

  1. Air
  2. Water
  3. A viscous gel or grease Correct answer.
  4. A dry film

Explanation

A viscous couplant stays in place on rough or vertical surfaces and fills surface irregularities to transmit sound. Water runs off easily, air transmits poorly, and a dry film provides little acoustic coupling.

Question 10Ultrasonic Testing (UT) Method Fundamentals and Principles

The purpose of the damping material in a transducer is to:

  1. Increase the output amplitude
  2. Focus the beam
  3. Shorten the pulse by suppressing ringing Correct answer.
  4. Change the beam angle

Explanation

Backing material absorbs energy and mechanically damps the crystal so it stops vibrating quickly, producing a shorter pulse and better resolution. It reduces rather than increases output, and it does not focus or steer the beam.

Question 11Ultrasonic Testing (UT) Method Fundamentals and Principles

Two indications appear on the display separated by a time interval equal to half the round-trip time through the part thickness; this pattern most likely represents:

  1. A single flaw echo
  2. Multiple back-wall reflections Correct answer.
  3. Electrical noise
  4. A dead zone

Explanation

Repeated echoes spaced at the part's round-trip interval are multiples caused by reverberation between the entry surface and the back wall. A single flaw echo would not repeat at that spacing, and noise or dead zone do not produce evenly spaced reverberations.

Question 12Ultrasonic Testing (UT) Method Fundamentals and Principles

In an A-scan display, an indication whose height increases as gain is reduced and whose position stays fixed most likely comes from:

  1. Instrument drift
  2. Random electrical noise
  3. A loose cable connection
  4. A real reflector within the beam Correct answer.

Explanation

A genuine reflector responds predictably to gain changes while keeping a fixed time position, consistent with a physical discontinuity in the sound path. Noise, cable faults, and drift tend to be unstable or position-shifting.

Question 13Ultrasonic Testing (UT) Method Fundamentals and Principles

The acoustic velocity of a longitudinal wave in a material is primarily determined by the material's:

  1. Elastic constants and density Correct answer.
  2. Grain size
  3. Surface finish
  4. Couplant

Explanation

Velocity is set by the elastic modulus and density of the medium according to the wave equation. Surface finish, grain size, and couplant affect transmission and attenuation but not the intrinsic bulk velocity.

Question 14Ultrasonic Testing (UT) Method Fundamentals and Principles

As frequency increases while velocity is held constant, the wavelength:

  1. Stays the same
  2. Increases
  3. Decreases Correct answer.
  4. Becomes zero

Explanation

Wavelength equals velocity divided by frequency, so raising frequency shortens wavelength. Higher frequency gives smaller wavelengths and improved resolution but greater attenuation.

Question 15Ultrasonic Testing (UT) Method Fundamentals and Principles

Beam divergence from a circular transducer is reduced by:

  1. Increasing frequency and crystal diameter Correct answer.
  2. Increasing gain
  3. Decreasing frequency and crystal diameter
  4. Reducing pulse repetition rate

Explanation

Divergence angle decreases with larger aperture relative to wavelength, so higher frequency (shorter wavelength) and larger diameter produce a more collimated beam. Gain and PRF do not change the physical beam spread.

Question 16Ultrasonic Testing (UT) Method Fundamentals and Principles

A 5 MHz transducer operating in a material with a longitudinal velocity of 5900 m/s produces a wavelength of approximately:

  1. 1.18 mm Correct answer.
  2. 5.9 mm
  3. 29.5 mm
  4. 0.85 mm

Explanation

Wavelength equals velocity divided by frequency, so 5900 m/s divided by 5,000,000 Hz gives about 0.00118 m, or 1.18 mm. The other values result from incorrect arithmetic or unit handling.

Question 17Ultrasonic Testing (UT) Method Fundamentals and Principles

The first critical angle is reached when the refracted longitudinal wave:

  1. Disappears entirely
  2. Reflects straight back
  3. Travels along the interface at 90 degrees Correct answer.
  4. Becomes a shear wave

Explanation

At the first critical angle the refracted longitudinal wave is bent to 90 degrees and travels along the interface; beyond it only the shear wave continues into the second medium. The longitudinal wave does not become a shear wave or reflect straight back at this angle.

Question 18Ultrasonic Testing (UT) Method Fundamentals and Principles

When using a straight-beam longitudinal probe to inspect a thin plate, the region immediately below the entry surface where flaws cannot be resolved is called the:

  1. Far field
  2. Shadow zone
  3. Dead zone Correct answer.
  4. Focal zone

Explanation

The dead zone is the near-surface region where the transmit pulse and ring-down mask echoes from small reflectors. The far field, focal zone, and shadow zone describe other beam regions.

Question 19Ultrasonic Testing (UT) Method Fundamentals and Principles

The pulse repetition frequency of an ultrasonic instrument must be kept low enough to avoid:

  1. Beam divergence
  2. Ambiguous or phantom signals from previous pulses Correct answer.
  3. Excessive gain
  4. Couplant loss

Explanation

If pulses are emitted too rapidly, echoes from a prior pulse may still be traveling in the part when the next pulse is sent, producing false or ambiguous indications. Gain, couplant, and divergence are unrelated to pulse timing.

Question 20Ultrasonic Testing (UT) Method Fundamentals and Principles

In a material with high attenuation, which change best compensates to maintain usable echo amplitude at depth?

  1. Higher PRF
  2. Higher frequency
  3. Lower frequency Correct answer.
  4. Larger beam angle

Explanation

Attenuation rises with frequency, so lowering frequency reduces loss and preserves penetration in highly attenuating materials. Raising frequency worsens attenuation, and beam angle or PRF do not address energy loss.

Question 21Ultrasonic Testing (UT) Method Fundamentals and Principles

A shear wave is generated in a solid at an angle from a longitudinal wave in a plastic wedge by the process of:

  1. Back-wall reflection
  2. Piezoelectric resonance
  3. Beam focusing
  4. Mode conversion at refraction Correct answer.

Explanation

When a longitudinal wave refracts obliquely into a solid, part of the energy converts to a shear wave, allowing angled shear-wave inspection. Resonance, reflection, and focusing do not create the refracted shear mode.

Question 22Ultrasonic Testing (UT) Method Fundamentals and Principles

The acoustic impedance of a material with density 7800 kg/m^3 and longitudinal velocity 5900 m/s is approximately:

  1. 46 x 10^6 kg/(m^2 s) Correct answer.
  2. 0.76 x 10^6 kg/(m^2 s)
  3. 1.32 x 10^6 kg/(m^2 s)
  4. 13.7 x 10^6 kg/(m^2 s)

Explanation

Impedance is density times velocity, so 7800 times 5900 gives about 46 million kg/(m^2 s). The other values result from dividing instead of multiplying or from arithmetic errors.

Question 23Ultrasonic Testing (UT) Method Fundamentals and Principles

Two reflectors produce equal A-scan amplitudes, but one is oriented perpendicular to the beam and the other is tilted. The tilted reflector's true size is likely:

  1. Larger than the perpendicular one Correct answer.
  2. Unrelated to orientation
  3. Identical to the perpendicular one
  4. Smaller than the perpendicular one

Explanation

A tilted reflector returns less energy to the transducer, so to produce the same displayed amplitude it must be larger than a well-oriented reflector. Orientation strongly affects echo amplitude, so equal amplitudes do not imply equal sizes.

Question 24Ultrasonic Testing (UT) Method Fundamentals and Principles

When the sound beam strikes an interface at an oblique angle, the transmitted beam direction is governed by:

  1. Beer's law
  2. Ohm's law
  3. Snell's law Correct answer.
  4. Hooke's law

Explanation

Snell's law relates the sine of incidence and refraction angles to the velocities in the two media. Hooke's law describes elasticity, Beer's law concerns absorption of light, and Ohm's law is electrical.

Question 25Ultrasonic Testing (UT) Method Fundamentals and Principles

A focused transducer is used to improve the detection of small flaws at a specific depth because focusing:

  1. Concentrates sound energy at the focal zone Correct answer.
  2. Eliminates all attenuation
  3. Increases the pulse repetition rate
  4. Raises the acoustic velocity

Explanation

Focusing concentrates energy into a smaller volume at the focal zone, raising sensitivity and resolution there. It does not change PRF, remove attenuation, or alter material velocity.

Question 26Ultrasonic Testing (UT) Method Fundamentals and Principles

Which display presentation shows the full cross-sectional profile of the part with the sound path plotted along one axis and the beam index position along the other?

  1. B-scan Correct answer.
  2. A-scan
  3. S-scan
  4. C-scan

Explanation

A B-scan plots echo amplitude as brightness while one axis represents sound path (time) and the other represents transducer position, producing a side-view cross-section. An A-scan shows amplitude versus time only, and a C-scan is a plan view.

Question 27Ultrasonic Testing (UT) Method Fundamentals and Principles

Which material property controls how much sound energy is reflected at a boundary between two different media?

  1. The surface roughness of the transducer face
  2. The pulse repetition frequency of the instrument
  3. The grain size of the first medium
  4. The acoustic impedance mismatch between the two media Correct answer.

Explanation

The reflection coefficient at an interface depends on the acoustic impedances of the two materials, since impedance is density times velocity. A large mismatch reflects most of the energy, while a close match transmits most of it.

Question 28Ultrasonic Testing (UT) Method Fundamentals and Principles

What does the vertical height of an indication on an A-scan display represent?

  1. The beam divergence angle
  2. The depth of the reflector
  3. The amplitude of the received echo Correct answer.
  4. The sound velocity in the part

Explanation

On an A-scan the vertical axis is calibrated in echo amplitude, so the height of an indication reflects the strength of the returning signal. Depth is read from the horizontal axis, and velocity and divergence are not displayed directly.

Question 29Ultrasonic Testing (UT) Method Fundamentals and Principles

An operator increases the test frequency on the same transducer diameter and material. What is the expected effect on beam spread in the far field?

  1. The beam becomes wider because wavelength increases
  2. The beam becomes wider because wavelength decreases
  3. The beam becomes narrower because wavelength decreases Correct answer.
  4. The beam spread stays the same because velocity is unchanged

Explanation

Far-field divergence is governed by the ratio of wavelength to crystal diameter, so a shorter wavelength at higher frequency produces a narrower beam for a given crystal size. Velocity is unchanged, so wavelength falls as frequency rises.

Question 30Ultrasonic Testing (UT) Method Fundamentals and Principles

A longitudinal wave in water strikes a steel surface at normal incidence. Which statement best describes the waves produced in the steel?

  1. Only a longitudinal wave is transmitted into the steel Correct answer.
  2. No energy enters the steel because of the impedance mismatch
  3. Both longitudinal and shear waves are transmitted at different angles
  4. Only a shear wave is transmitted into the steel

Explanation

At normal incidence there is no mode conversion, so only a longitudinal wave propagates into the steel along the same direction. Shear waves are generated by mode conversion only when the beam strikes the interface obliquely.

Question 31Ultrasonic Testing (UT) Method Fundamentals and Principles

Why is a delay line or wedge material chosen with a relatively low acoustic velocity and low attenuation?

  1. To eliminate the need for a couplant during inspection
  2. To raise the refracted angle above the second critical angle
  3. To place the interface echo clear of the near-field and reduce unwanted reverberations Correct answer.
  4. To increase the acoustic impedance match with the test part

Explanation

A low-velocity delay material lengthens the travel time through the wedge so the part interface echo separates cleanly from the transducer ring-down and near-field effects. Low attenuation keeps the pulse sharp and minimizes spurious echoes within the wedge.

Question 32Ultrasonic Testing (UT) Method Fundamentals and Principles

During straight-beam inspection of a forging, a cluster of small indications produces a broad, low-amplitude grass-like pattern that rises and falls with gain but does not move in depth. What is the most likely interpretation?

  1. An electronic fault in the receiver circuit
  2. A large planar crack oriented perpendicular to the beam
  3. A lack of couplant under the transducer
  4. Inherent material noise from grain structure or microstructure Correct answer.

Explanation

A diffuse, depth-stable pattern that scales with gain is characteristic of scattered sound from grain boundaries or microstructure, common in coarse or forged material. Discrete reflectors such as cracks produce distinct, localized echoes rather than a broad grass pattern.

Question 33Ultrasonic Testing (UT) Method Fundamentals and Principles

Two transducers of the same frequency are compared: one has twice the crystal diameter of the other. How does the near-field length of the larger crystal compare?

  1. It is approximately four times longer Correct answer.
  2. It is approximately half as long
  3. It is approximately twice as long
  4. It is unchanged

Explanation

Near-field length varies with the square of crystal diameter divided by wavelength, so doubling the diameter increases the near-field length by a factor of about four. Frequency and wavelength are held constant in this comparison.

Question 34Ultrasonic Testing (UT) Method Fundamentals and Principles

Which condition must be satisfied for a valid angle-beam shear wave inspection of a weld?

  1. The selected angle must fall between the first and second critical angles Correct answer.
  2. The selected angle must exceed the second critical angle
  3. The selected angle must be below the first critical angle
  4. The selected angle must equal exactly 90 degrees

Explanation

Between the first and second critical angles only a refracted shear wave propagates in the part, which is the condition required for shear wave inspection. Below the first critical angle both modes exist, and above the second critical angle no wave enters the part.

Question 35Ultrasonic Testing Equipment and System Performance

In a basic pulse-echo ultrasonic flaw detector, what is the primary function of the receiver/detector stage?

  1. To synchronize the sweep with the pulser repetition rate
  2. To amplify the returning echo signal and convert it to a form suitable for display Correct answer.
  3. To physically position the transducer over the test surface
  4. To generate the high-voltage electrical pulse that excites the transducer

Explanation

The receiver amplifies weak returning echoes and rectifies/detects them so they can be displayed on the screen. The pulser generates the excitation pulse, and the sweep circuit controls timing, so those are separate functions.

Question 36Ultrasonic Testing Equipment and System Performance

What does the PRF (pulse repetition frequency) of a flaw detector represent?

  1. The gain setting of the receiver amplifier
  2. The frequency of the ultrasound wave emitted by the transducer
  3. The rate at which the display screen refreshes
  4. The number of times per second the transducer is excited to produce a pulse Correct answer.

Explanation

PRF is the rate at which the instrument fires excitation pulses, measured in pulses per second. It is distinct from the transducer's acoustic frequency and from display refresh.

Question 37Ultrasonic Testing Equipment and System Performance

Which transducer parameter most directly determines the axial (depth) resolution of a pulse-echo inspection?

  1. The acoustic impedance of the couplant
  2. The gain setting of the receiver
  3. The diameter of the transducer element
  4. The number of cycles in the emitted pulse and its damping Correct answer.

Explanation

Axial resolution depends on pulse length, which is governed by the number of cycles and how quickly the pulse decays (damping). Shorter, well-damped pulses give better depth resolution.

Question 38Ultrasonic Testing Equipment and System Performance

A straight-beam contact transducer is used to inspect a thick forging. The near-field length is primarily a function of which combination?

  1. Element diameter squared, acoustic frequency, and material velocity Correct answer.
  2. Receiver gain and screen size
  3. Element diameter and couplant viscosity
  4. Pulse repetition frequency and sweep delay

Explanation

Near-field length depends on the transducer element size, the wavelength (frequency and velocity), and the geometry, scaling with diameter squared and frequency. Couplant, gain, and PRF do not set the near-field length.

Question 39Ultrasonic Testing Equipment and System Performance

Which reference block is designed specifically to establish the time base (distance calibration) for straight-beam inspections across a range of thicknesses?

  1. An IIW-type block used only for angle-beam checks
  2. A V-notch calibration block
  3. A set of stepped-thickness blocks with known dimensions Correct answer.
  4. A cylindrical curved-surface block with a single radius

Explanation

Stepped or variable-thickness reference blocks with known dimensions let the operator set sweep timing against multiple known metal paths. V-notch and curved blocks serve other specific calibration purposes.

Question 40Ultrasonic Testing Equipment and System Performance

During calibration, an operator notices the back-wall echo amplitude on a known-thickness block is significantly lower than expected and cannot be raised with gain. Which instrument/transducer condition is the most likely cause?

  1. The screen brightness is too low
  2. The sweep delay is set too high
  3. Poor coupling or a damaged transducer element Correct answer.
  4. The PRF is set too low

Explanation

Low echo amplitude that gain cannot correct usually points to poor acoustic coupling or a degraded transducer element. Sweep delay, PRF, and brightness affect display or timing, not the acoustic signal strength itself.

Question 41Ultrasonic Testing Equipment and System Performance

What is the purpose of the DAC (distance-amplitude correction) curve on a flaw detector?

  1. To compensate for the natural decrease in echo amplitude with increasing depth Correct answer.
  2. To adjust the PRF for different materials
  3. To correct the sweep for nonlinearity across the screen
  4. To set the transducer frequency automatically

Explanation

A DAC plots echo amplitude versus distance from a reference reflector, allowing depth-dependent amplitude changes to be compensated so that evaluation is consistent. It does not correct sweep linearity or set frequency.

Question 42Ultrasonic Testing Equipment and System Performance

Which display presentation shows echo amplitude as vertical deflection and distance as horizontal position on a single A-scan trace?

  1. A-scan Correct answer.
  2. B-scan
  3. D-scan
  4. C-scan

Explanation

An A-scan is a one-dimensional plot of amplitude versus time/distance. B-scans show a cross-sectional view, C-scans a plan view, and D-scans a projected view.

Question 43Ultrasonic Testing Equipment and System Performance

An operator must verify horizontal linearity of the flaw detector's time base. Which approach is appropriate?

  1. Compare echo positions from multiple known-thickness steps against expected screen positions Correct answer.
  2. Measure the maximum echo amplitude at a single depth
  3. Check the PRF against a frequency counter
  4. Confirm the transducer frequency with a calibrated oscillator

Explanation

Horizontal (time-base) linearity is verified by comparing the displayed positions of echoes from known distances against their expected proportional positions. Amplitude, PRF, and frequency checks address other parameters.

Question 44Ultrasonic Testing Equipment and System Performance

Which factor most limits the maximum usable inspection depth when the PRF is set too high?

  1. Echoes from a previous pulse may appear within the current sweep, causing range ambiguity Correct answer.
  2. The receiver gain will automatically decrease
  3. The transducer will overheat and fail
  4. The screen will lose vertical linearity

Explanation

If the PRF is too high, echoes from one pulse have not returned before the next pulse is fired, so late echoes appear at wrong positions (ghost/phantom echoes). This creates range ambiguity.

Question 45Ultrasonic Testing Equipment and System Performance

A transducer's damping block is increased in thickness and acoustic absorption. What is the expected effect on the emitted pulse?

  1. Shorter pulse with broader bandwidth Correct answer.
  2. Longer pulse with narrower bandwidth
  3. Higher frequency with unchanged pulse length
  4. Lower frequency with longer pulse length

Explanation

Increased damping absorbs rearward energy and shortens the pulse, which broadens the frequency bandwidth and improves axial resolution. It does not raise or lower the center frequency in a simple way.

Question 46Ultrasonic Testing Equipment and System Performance

When selecting a couplant for a rough, vertically oriented surface, which property is most important?

  1. High viscosity to remain in place and fill surface irregularities Correct answer.
  2. Low acoustic impedance to minimize transmission
  3. High acoustic velocity to speed the test
  4. Low cost to allow frequent replacement

Explanation

On rough or vertical surfaces, a viscous couplant stays in place and fills gaps to maintain coupling. Impedance matching matters, but retention and gap-filling are the practical priority here.

Question 47Ultrasonic Testing Equipment and System Performance

A phased array system steers a beam electronically. What does the focal law primarily define?

  1. The timing delays applied to each element to steer and focus the beam Correct answer.
  2. The gain applied to the receiver for each element
  3. The physical spacing of the elements on the probe
  4. The pulse repetition frequency of the system

Explanation

Focal laws specify the delay pattern applied across elements to steer and focus the beam. Element spacing is a fixed probe property, and gain/PRF are separate settings.

Question 48Ultrasonic Testing Equipment and System Performance

What is the main purpose of a time-corrected gain (TCG) function on a modern flaw detector?

  1. To correct the sweep for nonlinearity across the screen
  2. To automatically set the PRF for the material
  3. To convert angle-beam to straight-beam indications
  4. To apply depth-dependent gain so echoes of equal size display at equal amplitude regardless of depth Correct answer.

Explanation

TCG applies a gain that increases with time/depth to compensate for beam spread and attenuation, equalizing the display of equal reflectors at different depths. It does not correct sweep linearity or set PRF.

Question 49Ultrasonic Testing Equipment and System Performance

Which check confirms that the vertical display of a flaw detector is linear over its amplitude range?

  1. Comparing echo amplitudes from reference reflectors of known relative sizes against expected screen heights Correct answer.
  2. Confirming the transducer frequency with an oscillator
  3. Verifying echo positions against known thickness steps
  4. Measuring the PRF with a frequency counter

Explanation

Vertical linearity is verified by checking that known amplitude ratios (e.g., from reference reflectors) produce proportional screen heights. Position checks address horizontal linearity, not amplitude.

Question 50Ultrasonic Testing Equipment and System Performance

A dual-element (TR) transducer is preferred for which inspection situation?

  1. Detecting near-surface defects where the transmit pulse would otherwise mask echoes Correct answer.
  2. Measuring material velocity with high precision
  3. Inspecting very thick sections requiring maximum penetration
  4. Producing a focused beam at great depth

Explanation

Separate transmit and receive elements reduce the dead zone, improving resolution of near-surface reflectors. Thick-section penetration and velocity measurement are better served by other configurations.