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Exposure Calculator

Major collection: Science & Technology
Object type: calculator
Maker: MIT, High Voltage Lab
Date made: 1943-10-20
Nomenclature: physics tools and equipment - research devices
Classification: tools and equipment

Wooden slide rule, painted white, marked with scales: Exposure time in seconds for a density of 1.0 above fog density on e.k. type A X-ray film [Steel thickness-inches, Relative speed, Type A Film total density, Target-film distance in inches, material] tube current in microamperes, equivalent steel thickness-inches. Labelled on front "2.0 Million Volts D. C. // High Voltage LAb, Bldg. 46 // Mass. Institute of Technology." On reverse: Instructions for use, development time/temperature chart for Kodak film. Body of this rule (1990.062.004.002) is a Lawrence/Engineering Instruments 10-B slide rule body. It is likely that Lawrence/Engineering Instruments manufactured this rule for the MIT High Voltage Laboratory.


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