Robert Millikan’s oil drop experiment measured the “elementary” value of this quantity, which is the smallest amount of this quantity that can exist on its own. For 10 points each:
[10e] Name this quantity, which is negative 1.602 times 10-to-the-minus-19 coulombs for an electron.
ANSWER: charge [accept elementary charge; prompt on q]
[10m] Conservation of charge is expressed as [read slowly] “the time derivative of charge density plus [this operation] applied to current density equals zero.” Gauss’s law states that this operation applied to the B-field equals zero, implying magnetic monopoles do not exist.
ANSWER: divergence [accept div or del dot or nabla dot; reject “del” or “dot” alone]
[10h] Per Noether’s (“NURR-tuh’s”) theorem, conservation of charge is a consequence of one of these conditions being invariant with respect to a transformation. Another one of these conditions sets the divergence of the vector potential to zero.
ANSWER: gauge [accept gauge invariance or Coulomb gauge]
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