A 7.6 cm (3 inches) thick test specimen is radiographed with a source having size of 1.3 cm (1/2 inch), the film is placed in contact with the test specimen. The source to film distance is 40.6 cm (16 inches).The geometric unsharpness obtained is:

Related MCQs

• Which of the following is the correct formula to use for calculating geometric unsharpness if F=source size, T=specimen thickness, D=source to object distance and Ug=geometric unsharpness:
• A good Cobalt-60 shot is made on a 7.6 cm (3 inches) steel casting using an exposure time of 10 minutes and a source-to-film distance of 91.5 (36 inches). If it is necessary to change the source-to-film distance to 61 cm (24 inches), what exposure time would produce a similar radiograph if all other conditions remain the same?
• Calculate geometric unsharpness for the following conditions: Source size = 2 mm × 2 mm; SFD = 700 mm; test piece thickness = 25 mm
• A bar that is 5 cm (2 inches) by 10 cm (4 inches) by 30.5 cm (12 inches) is being magnetized in the circular direction. About how many amperes are required using the perimeter approach?
• Which of the following test frequencies would generally provide the best penetration in a 12 inch thick specimen of coarse-grained steel?
• A radiographic exposure with 3700 GBq (100 Ci) source of Ir-192 using source to film distance of 60 cm results in a radiation intensity of 0.12 Gy/h (11.8 R/h) and a radiographic density of 2.5. The intensity of radiation needed to obtain the same density when the source to film distance is changed to120 cm is:
• If an exposure time of 60 seconds and source to film distance of 365.7 m (1200 feet) is necessary for a particular exposure, what exposure time would be needed for an equivalent exposure if the source- to-film distance is changed to 457.2 m (1500 feet)?
• In order to increase latitude so that thick and thin portions may be radiographed at reasonable viewing densities simultaneously:
• Source-to-object distance, object-to-film distance, and source size are the three factors that control the of the radiograph.
• When using a straight beam technique to examine a thick test piece what change(s) would you expect to see in back wall echo size as you approach the side of the test piece? (Transducer remains completely on test piece)