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A Level Biology Colorimeter PLS HELP

Why do we use red filter in the colorimeter used to quantitatively measure reducing sugar concentration using Benedicts test?

And what is the difference between transmission and absorption? Which one is measured using colorimeter?

Thank you so much
In the Benedict’s test, Benedict’s solution is blue, and the positive result is red - therefore if measuring absorption, on a scale where more absorption equates to a higher concentration of reducing sugar, a red filter will need to be used.
Transmission is when light passes through the solution - recording % transmission is recording the proportion of light which passes through your measured solution. Absorption is when light is absorbed by the solution, so does not pass through - % absorption and transmission should sum 100% for any solution. A colorimeter can measure both depending on the setting you put it at

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