1. What is Percent Transmittance?

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

Purpose: It's used in spectroscopy, chemistry, and physics to analyze material properties and light absorption.

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 material transparency, concentration in solutions, and optical properties.

4. Using the Calculator

Tips: Enter both intensity values in W/m². Incident intensity must be greater than zero. Results are given as percentages.

5. Frequently Asked Questions (FAQ)

Q1: What does 100% transmittance mean?
A: It means all incident light passes through the material (perfect transparency with no absorption or reflection).

Q2: What does 0% transmittance mean?
A: It means no light passes through (complete opacity or complete absorption).

Q3: How is transmittance different from absorbance?
A: Absorbance (A) is the negative logarithm of transmittance (A = -log(%T/100)).

Q4: What are typical units for light intensity?
A: Watts per square meter (W/m²) is standard, but other units can be used as long as both values have the same units.

Q5: Why might my calculated %T be greater than 100%?
A: This indicates measurement error, as %T cannot exceed 100% for passive materials (except in special cases like laser gain media).