Why Sugar Always Twists Light To The Right - Optical Rotation
Why Physics Stack Exchange recommends it
Physics Stack Exchange users link it when asking about or demonstrating optical rotation in sugar solutions and how molecular handedness affects polarised light.
Recommended by 3 people across 2 different months, 2020 to 2025.
What it is
Steve Mould explains why a sugar solution rotates the plane of polarised light, and why glucose always twists it to the right. He builds the idea from chirality (molecular handedness) and from linear polarisation as a superposition of left and right circular waves that see different refractive indices.
What people said
Recommends Turbotanten · 2020-08 · Physics Stack Exchange · on “Will table sugar twist polarized light?”
I recently saw this awesome video [this video] by Steve Mould where he explained that a sugar solution in water will turn polarized light in the clockwise direction. The explanation basically boils down to sugar molecules (glucose) having a handedness (they are chiral) and that linearly polarized light can be thought of as a superposition of circular polarized light in opposite directions which experience a different refractive index when interacting with the sugar solution. Now to my question ; If I want to replicate this experiment at home, will regular table sugar work, or do I need pure glucose, and if that is the case where can I get it? Many thanks! Edit 1 : I will get back with the results
Recommends Tim · 2020-08 · Physics Stack Exchange · on “Polarization of sunlight by the earth's atmosphere”
Related, but not the answer this question, instead an explanation of how “disorganised” molecules souls still polarise light: [this video]
Recommends mmesser314 · 2025-01 · Physics Stack Exchange · on “What are the rules for implementing the simplest 1D physical wave in software?”
Here is an example series of videos that shows how an understanding of light is important to understanding an optical puzzle about how sugar water affects polarized light. They use models of light to help understand light. Source code for the model is available in a link so that you could reproduce the animations on your computer. This is the 3blue1brown Physics [LINK] playlist. The first 5 videos on the list are the Optical Puzzles series. Start with the first one to understand why polarized light passing though sugar water is puzzling. This much requires a start on understanding light. The second one explains the puzzle and gives a much deeper understanding of light. It makes heavy use of
Cites rodrigo · 2021-10 · Physics Stack Exchange · on “Why do some oranges freeze while others don't at the same temperature?”
This video [this video] suggests that sugar solutions twist polarized light (dextrose, right?), so maybe you could use a pair of polarized filters (quite cheap) and measure the angle of polarization of a given amount of liquid.