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Mistake Master · AP Chemistry · Unit 3 · Step-Through Animation

Light as a Ruler

You'll learnto read concentration from absorbance, which rises linearly through A = εbc.

A beam goes into a coloured solution and a weaker beam comes out, and that is enough to measure a concentration without touching the sample. It works because absorbance rises in a straight line with concentration, and a straight line is a ruler you can read backwards. Eleven short steps; press Next for each one.

11 STEPS · 6 QUICK CHECKS · A = εbc · λmax = 620 nm · UNIT 3 CLOSER · v4

light in · light out · a straight line you can read backwards
Before you start
What you're looking at
A lamp, one cuvette of dye, and a detector: a beam of strength I₀ goes in and a weaker beam I comes out.
The question
How can light in and light out measure a concentration without touching the sample?
Step 1 / 11