Nephelometry is based on measurement of light that is ______ by the particles of a suspension.

• A. Reflected
• B. Absorbed
• C. Transmitted
• D. Emitted

Answer: (A)

Nephelometry measures light that is scattered by the particles in a suspension. The instrument detects the intensity of light redirected from the incident beam as it interacts with suspended particles, which is why “reflected” best describes what is measured. This scattered light, not the light that passes straight through (transmitted), nor the light that is absorbed, nor light that is emitted by the sample, is what the nephelometer records. Absorbed light would reduce the transmitted beam, a property captured by absorption photometry; transmitted light is the direct beam through the sample; emitted light would indicate fluorescence or luminescence, which nephelometry does not rely on.