Eddy Current Testing
Level I
1. The impedance of an eddy current test coil will increase if the:
a. test frequency increases.
b. inductive reactance of the coil decreases.
c. inductance of the coil decreases.
d. resistance of the coil decreases.
2. Which of the following test frequencies would produce eddy currents with the largest depth of
penetration?
a. 100 Hz
b. 10 kHz
c. 1 MHz
d. 10 MHz
3. To generate measurable eddy currents in a test specimen, the specimen must be:
a. a conductor.
b. an insulator.
c. either a conductor or an insulator.
d. a ferromagnetic material.
Level ll
1. The fill factor when a 1.26 cm (0.5 in.) diameter bar is inserted in a 2.54 cm (1 in.) diameter coil is:
a. 0.5 (50 percent).
b. 0.75 (75 percent).
c. I.O (100 percent).
d. 0.25 (25 percent).
2. If the characteristic frequency (fg) of a material is 125 Hz, the test frequency required to give an f/fg ratio of 10 would be:
a. 1.25 Hz
b. 12.5 Hz
c. 1.25 kHz
d. 12.5 kHz
3. For age-hardened aluminum and titanium alloys, changes in hardness are indicated by changes in:
a. retentivity.
b. permeability.
c. conductivity.
d. magnetostriction.
