How was radioactivity first discovered? By whom?
Solution 2Q :
Radioactivity was first discovered by Antoine-Henri Becquerel, a french physicist.
Henri Becquerel was researching on the discovery of X-rays. He hypothesized that X-rays were emitted in conjunction with phosphorescence. Phosphorescence is a type of photoluminescence related to fluorescence that re-emits the light it absorbs. To test this hypothesis, Becquerel placed crystals that were composed of potassium uranyl sulfate which is a compound known to phosphoresce that is placed on top of a photographic plate wrapped in black cloth. He then placed the wrapped plate and the crystals outside, to expose them to sunlight. Becquerel performed the experiment several times and always got the same result that the photographic plate showed a bright...