Question

The transmissivity (τ) of a glass window is 0.9 between 0.3 and 3 μm. For other wavelengths, it can be approximated as 0. What does the transmissivity value represent in this context?

Answer 1

The transmissivity of 0.9 of a glass window means that 90% of the light within the wavelength range of 0.3 to 3 μm is transmitted through the glass. Outside this range, the glass does not transmit light. A transmissivity (A) of 1.0 corresponds to 100% transmittance.

Step-by-step explanation:

The transmissivity (τ) value represents the fraction of incident light at certain wavelengths that can pass through a material — in this case, a glass window. The given transmissivity of 0.9 between 0.3 and 3 μm means that 90% of the light within this wavelength range will transmit through the glass, while for wavelengths outside of this range, the transmissivity can be approximated as 0, indicating no light transmits through. To express a transmissivity (A) of 1.0 in terms of percent transmittance (%T), which is commonly used in infrared (IR) spectroscopy and ultraviolet-visible (UV-vis) spectroscopy, one would state that there is 100% transmittance since all the incident light is transmitted without any absorption.