What Is the Beer-Lambert Law Absorbance & Transmittance Calculator?
The Beer-Lambert Law governs quantitative absorption spectroscopy in chemistry and molecular biology.
How Does the Beer-Lambert Law Absorbance & Transmittance Calculator Work?
Photons are absorbed by electronic transitions. Each incremental slice of solution absorbs a constant fraction of light.
Beer-Lambert Law Absorbance & Transmittance Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
A = \varepsilon \cdot l \cdot c, \quad \%T = 10^{-A} \times 100\%
Absorbance A is linearly proportional to molar absorptivity ε, optical path length l, and molar concentration c.
How to Use the Beer-Lambert Law Absorbance & Transmittance Calculator
- Enter the molar extinction coefficient in L/(mol·cm).
- Specify cuvette path length (default 1.0 cm).
- Provide sample concentration in mol/L.
Step-by-Step Example Calculation
Spectrophotometric Protein Assay
Input Values:
extinctionCoeff:1000
pathLength:1.0
concentration:0.001
Worked Steps: A 1 mM solution with ε = 1000 L/(mol·cm) in a 1 cm cuvette yields an absorbance of 1.000 AU and 10% transmittance.
Understanding Your Result
Absorbance (A): Unitless optical density value (AU).
Transmittance (%T): Percentage of incident light reaching the photodetector.
Factors That Affect the Result
- Wavelength: Extinction coefficient varies dramatically across absorption spectrum peaks.
When Should You Use This Calculator?
- DNA, RNA, and protein quantification (e.g. A260/A280 assays) and chemical kinetic monitoring.
Assumptions & Limitations
- Assumes monochromatic light, homogeneous non-scattering solution, and no chemical dimerization.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Standard Beer-Lambert formulation with exact optical conversion.