# Dictionary Definition

transmittance n : the fraction of radiant energy
that passes through a substance [syn: transmission]

# User Contributed Dictionary

## English

### Noun

#### Translations

fraction of incident radiation

- German: Transmissionsgrad
- Italian: trasmittanza
- Korean: 투과율

# Extensive Definition

In optics and spectroscopy, transmittance
is the fraction of incident light at a specified wavelength that passes
through a sample.

- \mathcal =

where I_0 is the intensity of the incident
light and I is the intensity of the light coming out of the sample.
The transmittance of a sample is sometimes given as a
percentage.

Transmittance is related to absorbance A as

- A = - \log_\mathcal\ = - \log_\left(\right)

- A = - \ln\mathcal\ = - \ln\left(\right)

From the above equation and the Beer-Lambert
law, the transmittance is thus given by

- \mathcal = e^,

where \alpha is the attenuation
coefficient and x is the path length. Note that the term
"transmission"
refers to the physical process of light passing through a sample,
whereas transmittance refers to the mathematical quantity.

transmittance in Czech: Transmitance

transmittance in German: Transmission
(Physik)

transmittance in Spanish: Transmitancia

transmittance in French: Transmittance

transmittance in Italian: Trasmittanza

transmittance in Portuguese: Transmissão
(física)