## Conceptual Physics (12th Edition)

When a diver points a flashlight upward toward the surface of the water at an angle of $20^{\circ}$ from the normal, the beam of light passes into the air above.
The critical angle for water is $48^{\circ}$. The angle in this problem is less than the critical angle, so the beam passes through to the air above. Some is reflected, but not all of it. This is discussed on page 532, and shown in Figure 28.38.