# Refraction of light

We are learning about refraction of light at school
and we did an experiment with a semi circle plexi glass
We shone a ray of light at the plexiglass at different angles to find out the different angles of refraction.
When we had the semicircle plexiglass upside down, meaning curved part pointing downwards, and shone a light through the centre to the straight side of the glass, our refracted rays went toward the normal. When the ratio sine of incident rays and sine of refracted rays were done, we found out that the numbers were constant( all 1.5) and i think this showed the index of refraction of the second medium. am i right?
and then we put the semicircle right side up, meaning curved part facing up, and shone a light throught the centre to the curved edges, the refracted rays moved away from the normal. When the ratio of sine of incident rays and sine of refracted rays were taken, the numbers were constant with 0.67. Does this just represent n2 / n1? so index of air / index of glass? (1.00029/1.5)??
and also at 42 degrees, the refracted rays were at 90 degrees and after that all the bigger angles of incident rays got reflected.
So my question is what is the significance of the number 0.67 and what is its relation to the first part of the experiment where i got the number 1.5?
..... i have to answer these two questions in two sentences....- -;;

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jnimagine said:
We are learning about refraction of light at school
and we did an experiment with a semi circle plexi glass
We shone a ray of light at the plexiglass at different angles to find out the different angles of refraction.
When we had the semicircle plexiglass upside down, meaning curved part pointing downwards, and shone a light through the centre to the straight side of the glass, our refracted rays went toward the normal. When the ratio sine of incident rays and sine of refracted rays were done, we found out that the numbers were constant( all 1.5) and i think this showed the index of refraction of the second medium. am i right?
and then we put the semicircle right side up, meaning curved part facing up, and shone a light throught the centre to the curved edges, the refracted rays moved away from the normal. When the ratio of sine of incident rays and sine of refracted rays were taken, the numbers were constant with 0.67. Does this just represent n2 / n1? so index of air / index of glass? (1.00029/1.5)??
and also at 42 degrees, the refracted rays were at 90 degrees and after that all the bigger angles of incident rays got reflected.
So my question is what is the significance of the number 0.67 and what is its relation to the first part of the experiment where i got the number 1.5?
..... i have to answer these two questions in two sentences....- -;;
Remember that $\frac{2}{3}=0.67$ and its inverse $\frac{3}{2}=1.5$.

geoffjb said:
Remember that $\frac{2}{3}=0.67$ and its inverse $\frac{3}{2}=1.5$.
so is that the relationship betweent the two?
their index of refraction are reciprocals of each other?

Question

Well I am doing a science fair experimenent on index of refraction, and I really want an answer to this very fast, my deadline is next week.

Anyway,
I want to know how can I measure the index of refraction with a laser, I will be using a semi -circle to do this project. The point of this experiement, is to find the index of refraction of water, with a laser using the semi circle.
What is the equation that I will be using in order to find the index of refraction of water with a semi circle?

I will also be testing different concentrations of sugar, 5%-30%.
All I want to know is what procedure can I follow to find the index of refraction for plain water, and of course the same steps will be used for finding it for water with different concentration of sugar.

Thank you