Radioflash is a term used (chiefly in sources from the United Kingdom) in early literature on the phenomena now known more widely as nuclear electromagnetic pulse, or EMP. The term originated in the early 1950s, primarily associated with the "click" typically heard on radio receivers when a nuclear bomb was detonated. It was later discovered that the phenomena was one part of the more wide-ranging set of effects resulting from EMPs after the detonation of nuclear and certain chemical weapons.