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So I read the following about electric charge from Fundamentals of Electric Circuits (fifth edition) by Charles K. Alexander and Matthew N.O. Sadiku :

"According to experimental observations, the only charges that occur in nature are integral multiples of the electronic charge e = - 1.602 X 10^(-19) C"

Now I understand what is meant by the "the only charges that occur in nature are integral multiples " part - it means that the charges only exist as 1e, 2e or -1e; it cannot exist as 1/2 e, 0.8654e or πe etc.

What I don't understand is: what am I supposed to deduce by knowing that charge only exists as integral multiples? What would happen if the charges existed, for example, as 0.5e?

DigiNin Gravy
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2 Answers2

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The simplest thing to deduce is that charge, when observed under the conditions of the experiment, only comes in 'packets' of 1e. The simplest way to ensure that is that there are 'particles', each having an integral charge.

This is the simplest deduction to make. From here, it would be total nonsense to suppose that charge comes in smaller packets, like e/2, or e/3.

That's why it comes as a surprise to most people when learning about quarks, the components of nuclear particles, that they do have a charge in units of e/3. You don't observe quarks under the conditions of Millikan's oil drop experiment. In fact you don't observe quarks directly at all, but that's a different question.

Neil_UK
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Under rather special conditions charge can be quantized in current flows at fractions of an electron charge

Both groups measured a small electrical current in a two-dimensional electron gas sandwiched between two semiconductor layers. Fluctuations in the current - shot noise - were used to measure the electrical charge of the carrier particles. The sample was chilled to less than 1 K and a strong magnetic field applied at right angles to the layers. By analysing the shot noise in this regime, both groups reported evidence that the electric current is carried by quanta with charge one-third that of the electron.

Dirk Bruere
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