What does a colorimeter measure?

Ok can you tell me what it measures in THIS experiment please- basically recently I did an experiment to see how temperature effects the permeability of the cell membrane by using a beetroot, I used a colorimeter well my teacher did lol. But what does it exactly measure in this experiment?

Reply 1

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Reply 2

Harantony

A colorimeter measures how much light is reaching its detector. So, what it does is it shines a light through the substance (in your case the cuvette of beetroot juice) and it detects how much light of that wavelength actually passes straight through and reaches the detector.

If the beetroot's membrane has a HIGH permeability, lots of pigment will escape the membrane and go into the water, making it darker/more coloured. The light from the colorimeter will therefore have a difficult time passing straight through, because coloured objects absorb light at certain wavelengths.

If the membrane has a LOW permeability, the water/solution will stay pretty much colourless so lots of light will come through and be detected. Imagine standing behind a fish tank: if the water is colourless, you can see straight through. If it's green, things become less clear. :smile: