What is the standard relationship between absorbance and transmittance in Beer-Lambert law?

What is the standard relationship between absorbance and transmittance in Beer-Lambert law?

• A. A = log10(T)
• B. A = -log10(T)
• C. A = log10(1/T)
• D. A = T^2

Answer: (B)

Absorbance is defined as the negative logarithm of the transmitted light fraction. Transmittance T is the fraction of light that passes through, so T = I/I0. The standard relationship is A = -log10(T), which is the same as A = log10(1/T). This logarithmic connection means absorbance increases as transmittance decreases, and it underpins the Beer-Lambert relation A = εlc, linking absorbance to concentration and path length. The other options don't fit because log10(T) would give negative values when light is transmitted and A = T^2 has no basis in the established definition.

Absorbance is defined as the negative logarithm of the transmitted light fraction. Transmittance T is the fraction of light that passes through, so T = I/I0. The standard relationship is A = -log10(T), which is the same as A = log10(1/T). This logarithmic connection means absorbance increases as transmittance decreases, and it underpins the Beer-Lambert relation A = εlc, linking absorbance to concentration and path length. The other options don't fit because log10(T) would give negative values when light is transmitted and A = T^2 has no basis in the established definition.