The diagram shows a ray of light incident on a boundary between air and glass - Edexcel - GCSE Physics - Question 2 - 2014 - Paper 1

To determine which diagram correctly depicts the ray of light after it meets the boundary between glass and air, we need to follow these steps:

1. Understanding Refraction and the Critical Angle: Since the critical angle for glass in air is 42°, any angle of incidence greater than this will result in total internal reflection. An angle of incidence of 30° is less than the critical angle, meaning refraction will occur, not total internal reflection.

2. Analyzing Each Option:

   • Diagram A: The light ray bends towards the normal when entering the air, which aligns with the scenario. This is a possible correct option.
   • Diagram B: The light ray is refracted correctly as it exits the glass into the air. This could also be a correct option.
   • Diagram C and Diagram D: Both do not show the behavior expected at the boundary, as they suggest incorrect refraction angles related to the critical angle.

3. Conclusion: After analyzing all diagrams, the answer is Diagram B, which depicts the ray correctly refracting out into the air at an angle less than the critical angle.