What produces an alternating magnetic field in eddy current testing?

Probe.

Current that is flowing through a circuit is measured in

amperes.

What do you use to detect differences between permeability variations and cracks?

Phase detection.

Eddy current inspection can do all of the following except?

Detect all subsurface cracks.

Effective depth of penetration is the depth in the inspection article at which the magnetic field strength or intensity of the induced eddy currents is reduced to what percent of the value at the surface?

5.

When a test coil is moved away from a part due to lift-off, magnetic coupling between the test coil and inspection part

is decreased.

What effect do surface eddy currents, the secondary field, and depth of penetration have on poor conductivity?

Weaker surface eddy currents, weaker secondary field, and a greater depth of penetration.

Which mode of operation has two small sensing coils wound side-by-side in the shape of two back-to-back capital D’s?

Differential.

Which type of eddy current coil has differential sensors that are directionally sensitive and provide detection of crack tips?

Conformal coil.

What happens when an eddy current probe coil arrangement is closer to the test surface?

Small cracks can be detected due to greater sensitivity.

Eddy current instruments must have all of these capabilities except?

Dependability.

Eddy current instruments are designed to measure what three signal qualities?

Amplitude, phase, and frequency.

What is used to detect disturbances in the magnetic field produced by passing an alternating current in a thin planar foil of doped yttrium iron garnet?

Magneto-optic imaging.

How do you remove dust when cleaning an eddy current instrument?

Use a lint-free cloth.

Paint or other nonconductive coatings should be removed when in excess of how much of an inch?

0.010.

What is the name of the location on an impedance plane at which an eddy current instrument is usually called the “good” or reference condition?

Null point.

What type of filter removes the low frequency components of the eddy current signal from the bridge?

High-pass.

Modulation analysis is useful in separating signals of interest from other signals and relies on the analysis of what?

Time.

While repeatedly scanning the 0.020 inch notch on an aluminum standard, vertical and horizontal gain must be increased to reach how much of the full screen height during initial nulling?

80 percent.

Inspection for cracks, measurement of conductivity, or hardness can often be complicated by what two factors?

Surface damage and manufacturing processes.

The direction of tensile stress cracks are often analyzed by

engineer stress tests and historical cracking in the part.

What type of defects are usually caused by repeated cyclic loading of a structure at lower stress levels than required for visible deformation in fastener holes?

Fatigue cracks.

Conductivity is commonly measured in units of

mho.

Alloy effects on conductivity are caused by all of these except?

Cold working.

Conductivity decreases about how much in percent International Annealed Copper Standard (IACS) for a 20° F temperature increase for aluminum alloys?

One.

What is conductivity probe selection based on?

Thickness.

What is the advancement of a wave through a medium by transferring energy from one molecule to another?

Propagation.

Ultrasonic vibrations generate by applying electrical energy to what part of the transducer?

Piezoelectric element.

Which wave mode is used extensively for thickness inspections, corrosion thinning, and for the detection of other defects parallel to the inspection surface?

Longitudinal.

What is the angle between an incident longitudinal wave and a line normal to the surface called?

Incident angle.

What is the term for a change in direction of an ultrasonic beam as it passes through the interface between two materials with different acoustic velocity?

Refraction.

Extending from the face of the transducer is an area characterized by wide variations in sound beam intensity known as

near field.

During beam spread, sound extends outward from the transducer and does what to intensity and distance?

Decreases in intensity with increasing distance.

Acoustic pressure directly relates to what in the material particle vibrations caused by sound waves?

Amplitude.

What is a fine-delay control used to compensate for transducer faceplate wear?

Zero offset.