What does NTU mean?

What does NTU mean?

• A. A measurement of the optical properties of a liquid that cause light rays to be scattered and absorbed rather than transmitted in straight lines through a sample
• B. A measure of water temperature
• C. The unit of turbidity
• D. A measure of pH

Answer: (A)

NTU is tied to turbidity, which is a measure of how cloudy water is due to suspended particles. The key idea is that turbidity depends on how these particles affect light: they scatter and absorb light, so less light passes straight through. The description that NTU represents this optical behavior—light being scattered and absorbed rather than transmitted—best captures what the unit is quantifying. Temperature and pH are unrelated to turbidity, so those options don’t fit. Saying it’s just the unit of turbidity is true but incomplete; NTU specifically expresses the amount of light scattering due to suspended solids.

NTU is tied to turbidity, which is a measure of how cloudy water is due to suspended particles. The key idea is that turbidity depends on how these particles affect light: they scatter and absorb light, so less light passes straight through. The description that NTU represents this optical behavior—light being scattered and absorbed rather than transmitted—best captures what the unit is quantifying. Temperature and pH are unrelated to turbidity, so those options don’t fit. Saying it’s just the unit of turbidity is true but incomplete; NTU specifically expresses the amount of light scattering due to suspended solids.