## Conceptual Physics (12th Edition)

When the mirror is tilted upward in the "nighttime" position, the light from trailing cars reflects from the silvered surface and bounces to the cabin ceiling. Meanwhile, the driver sees the light reflected from the front glass surface of the mirror. The front surface reflects about $4\%$ of incident light (page 523), which is enough to see cars and their headlights in the rearview mirror during nighttime driving.