Henri Becquerel's Discovery: Radioactivity

Henri Becquerel is renowned for a pivotal discovery in physics.

Key Discovery

• In 1896, Henri Becquerel accidentally discovered radioactivity.
• He observed that uranium salts emitted rays that could penetrate opaque materials and expose photographic plates, even in the dark.
• This phenomenon, termed "Becquerel rays" initially, was later named radioactivity by Marie Curie.

Other Options Analysis

• Infrared radiation was discovered by William Herschel.
• Ultraviolet light was discovered by Johann Wilhelm Ritter.
• X-Rays were discovered by Wilhelm Conrad Roentgen.

Therefore, Henri Becquerel discovered Radioactivity.