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| | isospin -- Encyclopædia Britannica |
 | | The families of similar particles are known as isospin multiplets: two-particle families are called doublets, three-particle families are called triplets, and so on. |
 | | As early as 1920, when Rutherford named the proton and accepted it as a fundamental particle, it was clear that the electromagnetic force was not the only force at work within the atom. |
 | | In particular, values of mass, electric charge, spin, isospin, and strangeness gave physicists a means of classifying the strongly interacting particlesor hadronsand of establishing a hierarchy of relationships between them. |
| www.britannica.com /eb/article-9042967?tocId=9042967 (352 words) |
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