atomic bomb

An atomic bomb is composed of some heavy-duty explosives, capacitors, U-235 or P-239, and a neutron source.

The neutron source is in the center, surrounded by the Uranium or Plutonium, and then the explosives. Upon detonation, the capacitors all detonate the explosives simultaneously, crushing the nuclear material in on the neutron source. This causes the material to achieve critical mass and a massive chain reaction takes place.

Boom.

According to 'The Birth of the Bomb' by Ronald Clark, 1962, the British actually raised the possibility of a uranium bomb in a committee meeting just before Christmas 1939. A second memo in July 1941 commented that nuclear weapons might be possible 'before the end of the war'. In 1942-43, a research establishment was built next to a poison gas factory in Wales to test the equipment needed to refine Uranium. The British played a key role in encouraging the Americans to start their own nuclear program because they had the sense to realise they didn't have the resources to do it alone.