North Korea said on Wednesday that it had exploded a hydrogen bomb. This made a lot of people around the world very angry because North Korea is not meant to be testing those kinds of weapons. Here are 5 things you need to know about H-bombs
- Experts say the H-bomb (H stands for hydrogen) can be up to 1,000 times more powerful than the atomic bombs which were dropped on Japan at the end of the second world war.
- Atomic bombs use fission, or atom-splitting, just as nuclear power plants do. The hydrogen bomb, also called the thermonuclear bomb, uses fusion, or atomic nuclei coming together, to produce explosive energy. Stars also produce energy through fusion.
- Both the A-bomb and H-bomb use radioactive material like uranium and plutonium for the explosive material.
- The H-bomb has never been dropped on any targets, although both the US and the former Soviet Union have tested them.
- The H-bomb can be small enough to be fitted to a rocket called an ICBM (intercontinental ballistic missile) which can reach half-way around the world.