Eli5: My bicycle light warns of radiation if you stare directly at the light. Why isn’t simply touching or being next to it an issue?

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Eli5: My bicycle light warns of radiation if you stare directly at the light. Why isn’t simply touching or being next to it an issue?

In: Physics

This might be a bad translation or bad wording. It’s extremely unlikely that a bicycle light would emit harmful (ionizing) radiation other than light. Light is technically radiation, so that’s where the translation error may come in. Chances are they’re just telling you not to look directly at a bright light source.

The definition of radiation is energy emitted as electromagnetic waves or moving subatomic particles. Many people imagine nuclear radiation when they hear “radiation”, but that isn’t the only kind.

For example, light is radiation. Your bike light is warning you that staring into a bright light can hurt your eyes.

Probably not the case with your bike light, but certain kinds of light can do damage to your eyes without you realizing it.

For instance, monitoring equipment for volatile organics (called photoionization detectors-PIDs for short) use a UV lamp to help detect vapors. They come with a warning not to look into the meter at the light, because it can destroy/”burn” your retina.

P.S. And light (visible to us or not) is a form of “radiation” aka electromagnetic radiation.