1. What is Percent Transmittance?

Definition: Percent transmittance (%T) measures how much light passes through a water sample compared to the initial light intensity.

Purpose: It helps assess water clarity and purity, important for environmental monitoring and water treatment processes.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \%T \) — Percent transmittance (%)
• \( I \) — Transmitted intensity (W/m²)
• \( I_0 \) — Incident intensity (W/m²)

Explanation: The ratio of transmitted to incident light intensity is multiplied by 100 to get a percentage value.

3. Importance of Transmittance Measurement

Details: Transmittance measurements help determine water quality, presence of contaminants, and effectiveness of filtration systems.

4. Using the Calculator

Tips: Enter both intensity values in W/m². Incident intensity must be greater than zero. Results range from 0% (complete absorption) to 100% (complete transmission).

5. Frequently Asked Questions (FAQ)

Q1: What's a typical %T for clean water?
A: Pure water typically has >90% transmittance in the visible spectrum.

Q2: How does wavelength affect transmittance?
A: Water transmits visible light well but absorbs infrared and ultraviolet wavelengths more strongly.

Q3: What causes low transmittance in water?
A: Suspended particles, dissolved organic matter, algae, or other contaminants reduce transmittance.

Q4: How is this different from absorbance?
A: Absorbance (A) is related logarithmically: \( A = -\log_{10}(\%T/100) \).

Q5: What instruments measure transmittance?
A: Spectrophotometers or turbidimeters are commonly used for precise measurements.