Science Buddies: "Ask an Expert"

I am doing the project titled " Measuring Sugar content of a liquid using a Laser pointer" from https://www.sciencebuddies.org.
I have the following questions -

1. Why is a prism used to measure the refraction of light in the experiment ? Why can't a glass rectangle be used
instead ? Light should refract when going from air to the solution in the rectangle too.

2. Does using a prism make it easier to observe and measure the refraction of light ? If so then how ?

thanks
ak

dear akascience,

regarding your question, by looking at the experiment I see that a triangular prism is used, rather than a rectangular prism, which will refract light differently than a rectangular prism. If you want you can make your own prism as stated in the experiment (https://www.sciencebuddies.org/science- ... p028.shtml); look at the Making the Prism from Microscope Slides section of the experiment. Also, here are some links for information on prisms http://en.wikipedia.org/wiki/Prism_(optics) http://en.wikipedia.org/wiki/Dispersive_prism

Also, I want you to remember to be careful while working with lasers because they can be dangerous. You should follow all the safety procedures mentioned in the science buddies laser safety guide https://www.sciencebuddies.org/mentorin ... fety.shtml

good luck,
scienceexpert123

Why is a prism used to measure the refraction of light in the experiment ?

Because that is what the person who wrote up the experiment chose to use.

Why can't a glass rectangle be used instead ?

You should be able to use a rectangle as well; however, with the equilateral triangle setup, you can easily allign the incident angle so that the interior light path is parallel to one side so that the refractive angle and internal incident angle are equal which makes the math easier. With a square, you can allign to the diagonal and accomplish the same thing. With a rectangle, you will have to construct something at 45 degrees to allign to.