Experiment on finding the refractive indices of colours

[apples and pears]

Hi all! I'm trying to create a experiment so that i can find to refractive indicies of 3 colours... I attached the experiment setup but I don't know if it'll work... I thought about using Snell's Law to find the refractive indicies of the colors by first measuring the angles at the place where the light refracts out of the prism...

I'd appreciate your suggestions/opinions.

Thank You!