The working of a hydrogen bomb is based on two nucleur reactions - nucleur fission and nucleur fusion.Nucleur fission takes place when a uranium 235 nucleus is bombarded by a slow moving electron into 2 light nuclei barium-141 and krypton-92 . During this process a tremendous amount of energy is released in the form of heat and the heat produced during the process is utilised in the next reaction of nucleur fusion where 2 heium nuclei combines to form a hydrogen atom and this releases a tremendous amount of heat energy