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Exposure Maintenance Formula

Jul 29, 2024

Lecture Notes: Exposure Maintenance Formula

Introduction

  • Exposure Maintenance Formula is also known as the Density Maintenance Formula.
  • Example numbers are taken from the exposure lecture handout.
  • Steps will be fully worked through; no need for the handout.

Identifying Variables

  1. Identify Variables

    • Given: (Variables) SID1, mAs1, SID2
    • Example: SID1: 40 inches, mAs1: 40, SID2: 72 inches
    • Unknown: mAs2
  2. Setup Variables in Formula

    • Formula: (mAs1 / mAs2) = (SID1² / SID2²)
    • Substitute example values: (40 mAs / mAs2) = (40² / 72²)
  3. Cross Multiply

    • Equation after cross-multiplying:
      • (mAs1 × SID2²) = (mAs2 × SID1²)
    • Substitute values: (40 × 72²) = (mAs2 × 40²)
  4. Isolate the Unknown Variable (mAs2)

    • Equation after simplifying:
      • mAs2 = (40 × 72²) / 40²
    • Simplified further: mAs2 = 129.6

Calculation Steps

  • Cross-multiplying spreadsheets:
    • Top: 40 × 72² = 107,360
    • Bottom: 40² = 1,600
  • Division result: mAs2 = 129.6

Final Answer

  • mAs2 = 129.6
    • Recommend rounding to the nearest tenth place.
    • Check with your instructor for rounding preferences.

Summary

  • Successfully solved the Density Maintenance Formula.
  • Process involves identifying variables, setting up the formula, cross-multiplying, isolating the unknown variable, and solving.