 Home - General Resources - Formulas and Calculators

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Inverse Square Law
Exposure -  Distance
Reciprocity Law Where:

 I1 = Intensity 1 at D1 I2 = Intensity 2 at D2 D1 = Distance 1 from source D2 = Distance 2 from source

Inverse Square Law
Calculation Where:

 E1 = Exposure at D1 E2 = Exposure at D2 D1 = Distance 1 from source D2 = Distance 2 from source

Exposure-Distance Calculation Where:

 C1 = Current 1 C2 = Current  2 T1 = Time 1 at C1 T2 = Time 2 at C2

Current-Time Reciprocity Calculation

Film Density - Exposure

Geometric
Magnification
Geometric Unsharpness Note: This is an approximation and is only valid for the straight line portion of the film characteristic curve.  See more info section.
Where:

 E1 = Exposure 1 E2 = Exposure 2 FD1 = Film Density at Exposure 1 FD2 = Film Density with Exposure 2

Film Density - Exposure Calculation Where:

 M = Magnification a = Distance from source to object b = Distance from object to detector

Geometric Magnification Calculation Where:

 Ug = Geometric unsharpness f = Focal spot size a = Distance from source to object b = Distance from object to detector

Geometric Unsharpness Calculation

Indication Depth

Attenuation

Half-Value Layer Where:

 D = Defect depth from the film side of the part t = Thickness of material SD = Shift of defect image on the film SM = Shift of surface marker on the film

Indication Depth Calculation Where:

 Ix = transmitted intensity Io = Original intensity m = Linear attenuation coefficient x = Distance in material or material thickness 