Which device measures the refractive index of a solution?

Which device measures the refractive index of a solution?

• A. Refractometer
• B. Thermometer
• C. Balance
• D. Spectrophotometer

Answer: (A)

Refractive index is a measure of how much light slows and bends when it enters a substance. A refractometer is built to measure that bending directly. It shines light into the liquid on a precise prism and observes how the light changes direction (or the critical angle) at the boundary. Using this optical behavior, the instrument calculates the refractive index and displays it on a scale. Temperature can affect the reading, so many refractometers include temperature compensation to keep the index accurate for the given conditions. The other devices serve different purposes: a thermometer gauges temperature, a balance measures mass, and a spectrophotometer assesses how much light a sample absorbs at specific wavelengths. Absorbance relates to concentration in some assays, but not to refractive index, which is about light bending rather than absorbance.

Refractive index is a measure of how much light slows and bends when it enters a substance. A refractometer is built to measure that bending directly. It shines light into the liquid on a precise prism and observes how the light changes direction (or the critical angle) at the boundary. Using this optical behavior, the instrument calculates the refractive index and displays it on a scale. Temperature can affect the reading, so many refractometers include temperature compensation to keep the index accurate for the given conditions.

The other devices serve different purposes: a thermometer gauges temperature, a balance measures mass, and a spectrophotometer assesses how much light a sample absorbs at specific wavelengths. Absorbance relates to concentration in some assays, but not to refractive index, which is about light bending rather than absorbance.