T.O. 33B-1-1
Glossary 27
EDGE EFFECT (ET): The effect on the magnetic field caused by the geometric boundaries of the test specimen. The
effect is large in magnitude and similar in phase to a large crack. Also called END EFFECT.
EFFECTIVE DEPTH OF PENETRATION: The depth within a material, under test, where the transmitted or induced
energy is sufficient to detect discontinuities (determine condition of interest). EDP is approximately equal to three
time’s standard DOP.
EFFECTIVE FOCAL SPOT (RT): An elongated, rectangular electron focus so angled that the focal spot size, as
viewed along the X-ray beam axis, is smaller and approximately square, thereby permitting increased total area loading
of the target for a given focal spot size.
ELASTIC AFTER-EFFECT: A lagging elastic recovery, of minor proportions, following a decrease in or removal of
the load.
ELASTIC CONSTANTS: Modulus of elasticity, either in tension, compression or shear, and Poisson’s ratio.
ELASTIC DEFORMATION: Change of dimensions accompanying stress in the elastic range, original dimensions
being restored upon release of stress.
ELASTIC LIMIT: The maximum stress to which a material may be subjected without any permanent strain remaining
upon complete release of stress.
ELASTICITY: That property of a material by virtue of which it tends to recover its original size and shape after
deformation.
ELECTRICAL NOISE: Extraneous signals caused by externally radiated electrical signals or from electrical
interferences within the ultrasonic instrumentation.
ELECTROCHEMICAL CORROSION: Corrosion that occurs when current flows between cathodic and anodic area on
metallic surfaces.
ELECTRODE SKID: In spot, seam or projection welding, the sliding of an electrode along the surface of the work.
ELECTROGALVANIZING: The process of electroplating zinc on iron or steel.
ELECTROMAGNET: A soft iron core surrounded by a coil of wire. The iron core becomes magnetic when an electric
current flows through the wire.
ELECTROMAGNETIC INSPECTION OR TESTING (ET): A nondestructive test method for engineering materials
including magnetic materials, which use electromagnetic energy having frequencies less than those of visible light to
yield information regarding the quality of test material. This term includes both eddy current testing and magneto-
inductive testing.
ELECTROMAGNETIC RADIATION (RT): Radiation consisting of electric and magnetic waves that travel at the
speed of light. Examples: light, radio waves, gamma rays, X-rays. All can be transmitted through a vacuum.
ELECTROMAGNETIC SPECTRUM: The wavelength range of the various forms of electromagnetic radiation.
ELECTROMOTIVE FORCE (EMF): The work or energy that causes the flow of an electric current. Expressed as
volts. It should be noted that the term “force” is a misnomer. However, the term is so well established that its use
continues in spite of its being incorrect.
