Hello everyone, I am currently taking grade 11 U physics. We are doing a lab (Refraction and Critical Angles) and I have no clue what two questions are asking for!! I just need help understanding the question!!!! Here are the questions:

1) Compare the Ѳc (theta) found experimentally against the Ѳc (theta) using the formula and actual values of n2 & n1. Comment on possible sources of error in this lab.

2) Describe an application of critical angle / total internal reflections.

The critical angle is the angle that a light ray strikes a surface so that total internal reflectance occurs. That's what you determined. Read this.

Total internal reflection - Wikipedia, the free encyclopedia

The errors may be that you have a protractor which is not properly scaled, the light source moved between readings, the glass block moved and so on.