Question: What is the critical angle for total internal reflection from glass (n=1.5) to air (n=1)?

Options:

1. 41.8 degrees
2. 48.6 degrees
3. 60 degrees
4. 90 degrees

Correct Answer: 41.8 degrees

Solution:

The critical angle can be calculated using sin(θc) = n2/n1, which gives θc = sin^(-1)(1/1.5) = 41.8 degrees.