1. What is Percent Transmittance?

Definition: Percent transmittance (%T) measures the fraction of incident electromagnetic power that is transmitted through a material.

Purpose: It's commonly used in optics, electrical engineering, and spectroscopy to quantify how much light or energy passes through a medium.

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 intensity is multiplied by 100 to convert it to a percentage.

3. Importance of Percent Transmittance

Details: This measurement is crucial for designing optical systems, analyzing material properties, and ensuring proper signal transmission in electrical components.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What does 100% transmittance mean?
A: 100% means all incident energy passes through the material (perfect transmission), while 0% means complete absorption or reflection.

Q2: How is this different from absorbance?
A: Absorbance (A) is related logarithmically: \( A = -\log_{10}(\%T/100) \). They measure complementary properties.

Q3: What are typical %T values for common materials?
A: Glass might have 90-95%, sunglasses 10-40%, and metals often near 0%. Values vary with wavelength.

Q4: Can %T exceed 100%?
A: Normally no, unless the material amplifies the signal (like in lasers) or measurement errors occur.

Q5: How does wavelength affect %T?
A: Most materials have wavelength-dependent transmission properties (e.g., glass transmits visible light but blocks UV).