SIG FIGS in reading the SPECTROMETER

A spectrometer measures the amount of light passing through a given sample. In the spectrometers you will use in this course, this is measured as

  1. the per cent of the incoming light that is actually transmitted through the sample, Percent Transmittance, %T.

  2. the amount of incoming light that is absorbed by the sample, Absorbance , A.

On the Spectronic 20,

In this course you will read the % T scale. This scale is graduated into 1% units.To read this scale correctly, line up your eye so you do not see the reflection of the needle in the mirror and estimate the %T to 0.1% .

The meter on the Spectronic 20 spectrophotometer reads... 55.8 % T