: Days later, he developed the plate and found a clear, dark image of the crystals—meaning they were emitting "penetrating rays" spontaneously, without any external energy source like the sun.
: He was the first to realize that beta particles were identical to the high-speed electrons recently discovered by J.J. Thomson. antoine henri becquerel
: Inspired by the discovery of X-rays, Becquerel wanted to see if phosphorescent materials emitted X-rays after being exposed to sunlight. : Days later, he developed the plate and
Beyond the initial discovery, Becquerel’s research advanced the field in several ways: : Days later
: On a cloudy day in Paris, he placed uranium crystals on a photographic plate wrapped in black paper and tucked them in a dark drawer.