Explain the principle & structure of atom bomb.

Explanation

Atom bomb:
(i) The atom bomb is based on the principle of uncontrolled chain reaction. In an uncontrolled chain reaction, the number of neutrons and the number of fission reactions multiply almost in a geometrical progression.
(ii) This releases a huge amount of energy in very small time interval and leads to an explosion

Structures
(i) An atom bomb consists of a piece of fissile material whose mass is subcritical. This piece has a cylindrical void
(ii) It has a cylindrical fissile material which can fit into this void and its mass is also sub critical. When the bomb has to be exploded, this cylinder isinjected into the void using a conventional explosive.
(iii) The two pieces of fissile material join to form the supercritical mass, which leads to an explosion. During this explosion tremendous amount of energy in the form of heat, light and radiation is released.
(iv) region of very high temperature and pressure is formed in a fraction of a second along with the emission of hazardous radiation like `gamma` rays, which adversely affect the living creatures. This type of atom bombs were exploded in 1945 at Hiroshima and Nagasaki in Japan during the World War II