ET – Level 2

Level 2 ET

1 / 25

In ET, the specimen is coupled to the test coil by:

Core coupling

Magnetic saturation

The coil's magnetic field

Magnetic domains

2 / 25

It is often possible to sort various nonmagnetic alloys of a metal by means of ET when:

There is a unique range of permeability values for each alloy

There is a unique range of conductivity values for each alloy

The direction of induced eddy currents varies for each alloy

The magnetic domains for each alloy are different

3 / 25

The atoms of a metal showing magnetic characteristics are grouped into regions that are the smallest known permanent magnets. These regions are called:

Lattice structures

Cells

Domains

Planetary spins

4 / 25

The term used to define the difference between actual instrument output and expected output as defined by a straight line calibration curve is:

Phase shift

Nonlinearity

Lift-off

Skin effect

5 / 25

The conductivity value for a metal would most likely be influenced by which of the following factors?

Test frequency

Cold working performed on the metal

Magnetic field

Induced current

6 / 25

Non-ferromagnetic tubing is usually tested with multi-frequency ET techniques in the differential and absolute modes using a(n):

Through-transmission mode

Encircling coil

Surface coil

Bobbin coil

7 / 25

When a rod is placed in an encircling type of coil, the density of eddy currents will be the greatest:

At the surface

At the center

Midway between the surface and the center

At the applicable depth of penetration

8 / 25

Material must be reasonably centred in the test coil of a flaw detection system because:

The coil would otherwise be out of balance

Parts of the material furthest away from the coil may receive a less sensitive inspection

The flow of eddy currents around the product will be disturbed resulting in improper penetration

Lack of proper centering may change the phase adjustment of the instrument

9 / 25

A term used to define a system that indicates only the magnitude of variations in the total coil impedance regardless of the phase or direction in which it occurs on an impedance plane is:

Inductive reactance magnitude system

Feedback-controlled system

Impedance-magnitude system

Impedance vector analysis system

10 / 25

As the fill factor decreases, the impedance variation of a pickup coil produced by a given change in conductivity will:

Increase

Remain the same

Decrease

Affect the conductivity-to-permeability ratio

11 / 25

In a manufacturing environment, tubing is generally inspected using:

U-shaped coils

Gap coils

Encircling coils

Bobbin coils

12 / 25

An eddy current system using handling equipment with automatic marking of the defective areas primarily makes it possible to:

Remove defective areas of the product, if desired

Eliminate test surface contamination

Allow an inexperienced operator to establish the discontinuity cause

Pass rejectable material

13 / 25

When carrying out an eddy current test, discontinuities will most readily be detected when eddy currents are:

90 degrees out of phase with the current in the test coil

Perpendicular to the major plane of the defect

Parallel to the major plane of the defect

14 / 25

Which of the following materials would more likely be used to create a holding fixture for a probe coil?

Aluminium

Plastic

Copper

Steel

15 / 25

Doubling the number of turns on a coil will:

Double its inductance

Have its inductance

Decrease its inductance by approximately a factor of four

Increase its inductance by approximately a factor of four

Decrease its inductance by approximately a factor of four

16 / 25

When a direct current saturation technique is applied to a ferromagnetic material, the flux density in the material is:

Less than the flux density generated by the test coil because of heat losses

Less than the flux density generated by the test coil because of resistivity

The same as the flux density generated by the test coil

Greater than the flux density generated by the test coil

17 / 25

The bores of fastener on aircraft are an important source of cracking caused by:

Fatigue

Burst

Overloading

Any of the above

18 / 25

How could one decrease the effect of conductivity readings due to variations in the test piece thickness?

The fill factor could be reduced

The test frequency should be increased

The test frequency should be reduced

There is no practical way to decrease this effect

19 / 25

In order to decrease the effect on conductivity readings due to variations in test part thickness:

The test frequency should be increased

The test frequency should be decreased

The fill factor should be decreased

There is no practical method for decreasing this effect

20 / 25

The primary purpose(s) of the secondary winding in a test coil is to:

Induce eddy currents in the test specimen

Detect changes in the eddy current flow

Induce eddy currents in the test specimen and to detect changes in the eddy current flow

Provide DC saturation

21 / 25

When attempting to determine the exact point location of a discontinuity the test system should include:

A phase shifter

A probe attenuator

An attenuator

A penetrameter

22 / 25

When performing ET on tubing with a system that includes adjustable filter functions, which of the following variables would be classified as a high-frequency variable?

Small discontinuities

Conductivity changes

Diameter changes

Wall thickness variations

23 / 25

When conducting an electromagnetic test, variations in the test material can be detected as variations in:

Test speed

Impedance of a pickup coil

Test frequency)

Fill factor)

24 / 25

When the voltage applied to a circuit and the current through the circuit both reach their maximums and minimums at the same time, the voltage and current are:

Additive

In phase

Regenerative

Out of phase

25 / 25

The fill factor when a 12.7 mm diameter bar is inserted in a 25.4 mm diameter coil is:

0.5 (50 percent)

0,75 (75 percent)

1.0 (100 percent)

0.25 (25 percent)

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