eli5 How come if highly radioactive radium was on watches that the wearers didn’t succumb to radiation poisoning at the wrist?

Question

eli5 How come if highly radioactive radium was on watches that the wearers didn’t succumb to radiation poisoning at the wrist?

In: 186

Answer 1

Alpha radiation from radium consists of helium nuclei, which is a whole helium atom minus the electrons. These are (in relation to other forms of radiation) HUGE and easily stopped by almost anything, even a few centimeters of air are enough. You can shield yourself from alpha radiation literally by holding up a sheet of paper. So a watch or some thin glass cover would be sufficient.

I have a friend who has a uranium pellet encased in resin as a keychain, it was an official souvenir from visiting a nuclear power plant.