Why do transition lenses go dark in sunlight when you’re outside but not when you’re in a brightly lit room?

Question

Why do transition lenses go dark in sunlight when you’re outside but not when you’re in a brightly lit room?

In: 12

Answer 1

The lenses react to ultraviolet light (light that we can’t see but is still there; it’s the light that causes sunburn).

A bright room is probably a result of bulbs emitting mostly yellow light. This is the wrong frequency for the lens to react to, so it doesn’t. Even a white bulb (a mixture of frequencies) is emitting mostly visible light and not wasting energy by producing light we can’t see.