Spectrophotometry utilizes which principle?

• A. Color absorption
• B. Light reflection
• C. Light transmission
• D. Frequency modulation

Answer: (C)

Spectrophotometry is a method used to measure how much a chemical substance absorbs light by measuring the intensity of light as a beam passes through a sample solution. The principle behind this technique is primarily based on light transmission, which involves the amount of light that passes through a sample and how much of that light is absorbed by the sample.

When light is transmitted through a substance, certain wavelengths are absorbed depending on the characteristics of the substance, while others may pass through unaffected. The spectrophotometer quantifies this by measuring the transmittance and absorbance at specific wavelengths. This information helps in determining the concentration of the substance within the sample, as there is a direct relationship between concentration and the amount of light absorbed, described by Beer-Lambert's law.

By focusing on light transmission, spectrophotometry effectively provides insights into the absorbance behavior of different chemicals, allowing for quantitative analysis in various fields such as biology, chemistry, and environmental science.