How does the atomic bomb make an explosion?

Answer 1

Atomic bombs contain material capable of undergoing fission. Fission is a process whereby the nuclei of large unstable elements such as plutonium or uranium split into two smaller daughter nuclei, converting some of their mass to energy, which results in a large amount of heat. Fission naturally occurs in all samples of material capable of undergoing it, but it is the rate which allows heat to be released in a controlled manner, as in a nuclear reactor, or in the runaway explosion of a nuclear bomb.

The unstable nuclei which undergo fission are not normally present in high numbers in the radioactive material, due to their quick decay into daughter nuclei. Instead, they are created by the collision of a free neutron with a more stable nucleus, such as U-235. The now slightly larger nucleus (in this example U-236), rapidly undergoes fission, forming daughter products, giving off energy and releasing 3 more neutrons. These neutrons can then go on to hit further U-235 atoms and cause further fission, in a process known as a chain reaction. Although theoretically this means that the reaction will proceed at a faster and faster rate as more and more neutrons are released, in most cases the concentrations of U-235 atoms are low enough that most neutrons do not go on to collide with them and allow the reaction to proliferate. However, if U-235 is present in sufficient concentrations, and at a sufficient (critical) mass, then enough neutrons will be absorbed that once started the reaction will rapidly proceed to completion, releasing vast amounts of energy. This explains the importance of enriching Uranium (increasing the ratio of U-235 to U-238, which does not undergo fission). If Uranium is slightly enriched, then it can provide a suitable fuel for nuclear power stations, able to continue a fission reaction without letting it run out of control. However, if it is highly enriched (around 80% U-235), then the initiation of a fission reaction will result in a rapid runaway chain reaction releasing huge amounts of energy - the explosion.

This presents a problem, as the material must be enriched in advance of preparing the device. The material must therefore be arranged in the device in such a way that it does not allow a reaction to begin until some change is brought about to make it achieve a critical mass on detonation. For example, the Hiroshima bomb was made of 2 sections of fissile material, neither of which had a critical mass by itself. On detonation, a conventional explosive fired one section into the other section, causing the now larger sample of material to obtain a critical mass and undergo a chain reaction.

Answer 2

An atomic bomb (Such as "Little Boy" the bomb dropped on Hiroshima) is first set off by a conventional explosive, which propels a uranium cone into another piece of uranium shaped to that cone with such force that uranium atoms split apart and collide with other atoms, with each atom split, several more are split because of stray neutrons and protons, causing a chain reaction. The "Explosion" from an atomic bomb is actually a massive release of energy caused by the split atoms.

Answer 3

They are specially arranged in something like a cylinder in a form like fireworks so they light it whenever a superstar comes on stage.

Answer 4

when the flame gets to the bomb it reaches the gunpowder and sets of an irreversible explosion.