ASNT Level III: Ch. 4 (RT) Questions and Answers 100% Solved

ASNT Level III: Ch. 4 (RT) Questions and Answers 100% Solved The penetrating ability of an X-ray beam is governed by: kilovoltage or wavelength Two X-ray machines operating at the same nominal kilovoltage and milliamperage settings: may give not only different intensities but also different energies of radiation Short wavelength electromagnetic radiation produced during the disintegration of nuclei of radioactive substances is called: gamma radiation Almost all gamma radiography is performed with: artificially produced isotopes The energy of gamma rays is expressed by which of the following units of measurement: Kiloelectronvolts (keV) or megaelectronvolts (MeV) Of the following, the source providing the most penetrating radiation is: 15 MeV betatron The difference between the densities of two areas of a radiograph is called: radiographic contrast The fact that gasses, when bombarded by radiation, ionize and become electrical conductors makes them useful in: radiation detection equipment The reason exposure time must be increased by a factor of four when the source-to-film distance is doubled is that the: intensity of radiation in inversely proportional to the square of the distance from the source to the film The most importance factor in X-ray absorption of a specimen is: the atomic number of the material The maximum permissible does per calendar year is 5 rem (0.05Sv) for: whole body (total effective dose equivalent) Exposure to small doses of X-rays or gamma rays: has a cumulative effect that must be considered when monitoring for maximum permissible dose Which of the following technique variable is most commonly used to adjust subject contrast? Kilovoltage A basic difference between a radiograph and a fluoroscopic image is that: the fluoroscopic image is positive whereas the radiographic image is negative Thin sheets of lead foil in intimate contact with X-ray film during exposure increase film density because they: emit electrons when exposed to X- and gamma radiation, which helps to darken the film When viewing a radiograph, an image of the back of the cassette superimposed on the image of the specimen is noted. This is most likely due to: backscatter radiation An image quality indicator (IQI) is used to measure the: quality of the radiographic technique In film radiography, IQIs are usualy placed: on the source side of the test object At voltages about 400kV, the use of lead to provide protection may present serious structural problems. If this should be the case, which of the following materials would most likely be used as a substitute? concrete A distinctive characteristic of megavolt radiography is that it: is applicable to comparatively thick or highly absorbing specimens Given the radiographic equivalency factors of 1.4 for Inconel and 1.0 for 304 stainless steel, what is the approximate equivalent thickness of Inconel to produce the same exposure as 3.8mm (0.15in) thickness of 304 stainless steel? 3mm (0.11in) The fact that each solid crystalline substance produces its own characteristic S-ray pattern is the basis for: X-ray diffraction testing When inspecting a light metal casting by fluoroscopy, which of the following discontinuities would most likely be detected? Shrinkage For testing a 25 mm (1in) steel plate 305 mm (12 in) square for laminar discontinuities, which of the following would be most effective? An ultrasonic device A critical weld was made with a double vee-groove. Among those listed, which radiographic technique would provide coverage with the greatest probability for detecting the most serious discontinuities? Two exposures aligned with the vee-groove, focus +or- degrees off perpendicular A fuse assembly is radiographed so that measurements can be made on the film to determine a minimum internal clearance dimension. What should be factored into the dimension taken from the film? Projection magnification Miniature electronic components are to be radiographically inspected to reveal broken copper wire leads of 0.2 mm (0.008 in) diameter. Which of the following image quality indicators (IQIs) would be most effective to use in establishing a reliable technique? A plastic block with the radiographic thickness equivalent of the test objects, containing copper wire ranging from 0.1mm (0..5in) to 0.4mm (0.015in) diameter