How does measurement of turbidity differ from nephelometry?

• A. Turbidity measures the increase in light after it passes through a solution.
• B. Nephelometry measures light that is scattered at an angle.
• C. Turbidity deals with univalent antigens only.
• D. Nephelometry is not affected by large particles falling out of solution.

Answer: (B)

The main idea is how light interacts with particles in a solution. Turbidity measures cloudiness by looking at how much light is transmitted through the sample—suspended particles scatter and absorb light, so the amount that passes straight through is reduced. It doesn’t specify where the scattered light goes; it’s a general measure of how opaque the solution is.

Nephelometry, in contrast, is all about detecting light that has been scattered at a specific angle from the incident beam. By placing the detector at a set angle, nephelometry captures the signal from scattered light, which directly reflects particle concentration and characteristics in a way that’s less influenced by the unscattered beam.

So the correct idea is that nephelometry measures light scattered at an angle, whereas turbidity concerns overall cloudiness and transmission of light through the sample. Large particles and settling can affect both, but the defining feature of nephelometry is the angle-specific scattered-light measurement.