Use the handbook’s line-source approximation for a long source such as a pipe or run of contaminated tubing. Close to the source, intensity varies as 1/d, giving I₁d₁ = I₂d₂.
This approximation treats distances up to half the source length (L/2) as a line source and applies inverse-square behaviour beyond that boundary. The calculator checks both the known and target distances, including problems that cross the boundary. You can solve for intensity or distance.
Results, input checks, source references and accuracy notes are free. Paid membership adds the step-by-step solution and calculator keystrokesKey sequences for 14 calculator optionsScientific — commonly exam-legalTI-30XaTI-30X IIS / IIBTI-30XS MultiViewTI-34 MultiViewTI-36X ProCasio fx-991EX ClassWizCasio fx-115ES PlusCasio fx-300ES PlusSharp EL-W516TOn screen, no handheld neededRadCon calculator (on screen)Graphing / programmable — practice at homeTI-84 Plus CE (and TI-83/84 family)Casio fx-9750GIII / fx-9860GIIIHP 35sNot sure which you haveGeneric scientificChoose the calculator you use to practice. Check with your testing site which models are allowed in the exam..
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Use this calculator for study and reference. For operational radiological work, follow your site’s controlled procedures and approved references.
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