Radioactivity came to light a century after the discovery of uranium when Henri Becquerel used uranium salts and photographic plates in the same experiment and found that one fogged the other.

• 放射性是铀发现一百年之后才被贝克勒尔发现，他在同一个试验中使用了铀盐和显像版，结果发现前者是后者变得模糊。