FIELD, MAGNETIC (MT): The space within and surrounding a magnetized part or a conductor carrying current in
which magnetic lines of force exists.
FIELD, RESIDUAL (MT): The magnetism that remains in a piece of magnetizable material after the magnetizing
force has been removed.
FIELD, RESULTANT (MT): The magnetic field resulting when two or more magnetizing forces, operating in different
directions, are applied to ferromagnetic materials.
FILAMENT (RT): The source of electrons in a hot-cathode tube. It is usually a heated wire.
FILAMENT TRANSFORMER (RT): A transformer supplying power to heat the filament of a hot-cathode. The
primary and secondary windings must be sufficiently insulated to withstand the peak potential difference between the
cathode and earth.
FILLED CRACK: A crack-like discontinuity, open to the surface, but filled with some foreign material - oxide, grease,
etc. - which tends to prevent penetrants from entering.
FILLET: Radius imparted to the inside of two meeting surfaces.
FILL FACTOR (MT): The square of the ratio of the diameter of a part to the diameter of one encircling coil(s). The
square of the ratio of the internal coil diameter to the bore diameter for internal probes. The fill factor is a measure of
coupling between the encircling or internal coil and the test object.
FILM BADGE (RT): A piece of masked radiographic film worn in the form of a badge that is used to measure
exposure. The amount of exposure is determined from the degree of film blackening.
FILM BASE (RT): A flexible, transparent, or translucent material that is coated with a photosensitive emulsion.
FILM CLEARING TIME (RT): See CLEARING TIME. FILM CONTRAST (RT): See CONTRAST, FILM. FILM
DENSITY (RT): See DENSITY, FILM.
FILM GAMMA (RT): Term used to describe the amplification factor of a radiographic film, equal to the absolute slope
of the characteristic curve.
FILM GRAININESS (DIRECT X-RAY EXPOSURES) (RT): The visual impression of irregularity of density, in areas
where exposure is macroscopically uniform, due to the random spatial distribution of X-ray quanta absorbed in the
film. In general, fast films exhibit greater graininess than slow films.
FILM HOLDER (RT): A light-tight carrier for films and screens.
FILM ILLUMINATOR (RT): A device incorporating a suitable source of illumination for viewing radiographs or other
FILM LATITUDE (RT): Latitude refers to the exposure range within which a satisfactory radiograph is produced.
Films which have the widest latitude are those which have the lowest film gradient and therefore the lowest film
FILM PROCESSING (RT): See PROCESSING, FILM.
FILM, RADIOGRAPHIC (RT): A photographic film that is usually coated on both sides with an emulsion designed for
use with X-rays and gamma rays.
FILM RING (RT): A film badge worn as a ring to measure the exposure of the fingers to ionizing radiation.