🔬 UV-Vis Spectroscopy & Optical Absorption
Beer-Lambert Law Spectrophotometry Calculator
Calculate optical absorbance ($A$), percent transmittance ($\%T$), unknown molar concentration ($c$), and molar absorptivity ($\epsilon$) across standard cuvette path lengths.
Optical & Chemical Parameters
M⁻¹ cm⁻¹
cm (Standard = 1 cm)
Optical Absorbance (A)
0.750 AU
Percent Transmittance
17.78% %T
Light Absorbed
82.22% Light
Linearity Range
Optimal (0.1–1.0 AU) 🟢
💡 Spectrophotometer Validity:
Absorbance values between 0.1 and 1.0 AU fall within the linear dynamic range of standard UV-Vis photodetectors with lowest photometric noise error.
The Physics of Light Attenuation
The Beer-Lambert-Bouguer Law models photon absorption through a homogeneous medium:
$$A = \epsilon \cdot b \cdot c = -\log_{10}(T) = -\log_{10}\left(\frac{I}{I_0}\right) = 2 - \log_{10}(\%T)$$
- Transmittance ($T$): Ratio of transmitted light intensity $I$ to incident beam intensity $I_0$.
- Molar Absorptivity ($\epsilon$): Chemical fingerprint measuring how strongly a substance absorbs light at a given wavelength $\lambda$.