In the news: North Korea said Wednesday it had conducted a hydrogen bomb test
Hydrogen “H-bombs” vs Atomic “A-bombs”:
Compared with the atomic bomb (the kind developed in the Manhattan project and used at the end of the Second World War), the hydrogen bomb can be far more powerful. Atomic bombs rely on fission, or atom-splitting. The hydrogen bomb uses fusion, or atomic nuclei coming together, to produce explosive energy. Stars also produce energy through fusion.
Hydrogen bombs can be made smaller. H-bombs can fit on the head of an intercontinental missile.
What’s the same
Both the A-bomb and H-bomb use radioactive material like uranium and plutonium for the explosive material.
A-bombs split up large atoms in a chain reaction. If enough of a large atom gets together (the critical mass) it will spontaneously start to split up, releasing energy. A-bomb design is about controlling the chain reaction, usually by controlling the size, shape and position of the radioactive material pieces.
H-bombs stick generally small atoms together. To get the high energy needed to start the reaction, an A-bomb is used. The explosive power of an H-bomb is made up in part of the fission reaction from the A-bomb and the fusion reaction of the H-bomb. Since the fusion reaction will only start when the A-bomb is detonated, H-bombs can be made much bigger than A-bombs.
Find out More
The source of the energy is linked to the structure of atoms and how they are held together. It is more than just Einstein’s famous equation E=mc2, details can be found at this link.
An account of the first atomic bomb explosion from Richard Feynman can be found at this link.
Explore the effect of nuclear bomb detonations with the NUKEMAP simulator.
The biggest H-bomb ever detonated was in Russia in 1961 and is shown in the video above.