Donald Cook, age 13, of West Warwick, Rhode Island, for his question:

When was the first hydrogen bomb tested?

Compared with other nuclear explosions, the first hydrogen explosion was a small scale affair first tested in the spring of 1951. The test was directed by the U.S. Atomic Energy Commission and nuclear scientists were satisfied that this type of nuclear explosion was feasible. A major problem had been to find a suitable detonator to trigger off the mighty forces of this type of nuclear fusion bomb. The test proved that such a trigger could be provided by a nuclear fission explosion, already mastered in the A bomb. This works somewhat like a cap of hot tempered chemicals which is used to trigger a stick of dynamite.

Large scale hydrogen bombs were built soon after the first test. America exploded the first large scale fission fusion bomb on a remote coral atoll in the Pacific on November 1, 1952. It was a 60 ton bomb that exploded with the force equal to three million tons of TNT, which rated it as a three megaton bomb. This hydrogen bomb was 150 times more devastating than the A bomb used to wipe out the Japanese city of Hiroshima.