Understanding NRT- Reading 1- 2 of 2- Radiogaphic Testing A
Understanding nrt reading 1- 2 of 2- radiogaphic testing a
Understanding nrt reading 1- 2 of 2- radiogaphic testing a
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Applications <strong>of</strong> the reciprocity law over a wide intensity range sometimes<br />
arise, and the relation between results and calculations may be misleading<br />
unless the possibility <strong>of</strong> failure <strong>of</strong> the reciprocity law is kept in mind. Failure <strong>of</strong><br />
the reciprocity law means that the efficiency <strong>of</strong> a light-sensitive emulsion in<br />
utilizing the light energy depends on the light intensity. Under the usual<br />
conditions <strong>of</strong> industrial radiography, the number <strong>of</strong> milliampere-minutes<br />
required for a properly exposed radiograph made with fluorescent intensifying<br />
screens increases as the x-ray intensity decreases, because <strong>of</strong> reciprocity<br />
failure.<br />
If the milliamperage remains constant and the x-ray intensity is varied by<br />
changing the focus-film distance, the compensating changes shown in the<br />
table below should be made in the exposure time.<br />
Charlie Chong/ Fion Zhang
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