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Answer the following questions: (a) Qu...

Answer the following questions:
(a) Quarks inside protons and neutrons are thought to carry fractional charges `[(+2//3)e , (-1//3)e]`. Why do they not show up in Millikan’s oil-drop experiment?

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Quarks are thought to be confined within a proton or neutron by forces which grow stronger if one tries to pull them apart. It, therefore, seems that though fractional charges may exist in nature, observable charges are still integral multiples of e.
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