In a laboratory demonstration, a student investigates the total internal reflection of light in different plastic blocks.
Show, by calculation, that the critical angle c c\,c for a plastic block with a refractive index of 1.45 is approximately 44∘44^\circ44∘.
Explain why the physical quantity known as the refractive index has no unit.
Explain why total internal reflection at a boundary with air can only occur if the refractive index of the medium is greater than 1.0.