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Why is electron presented in books, pictures as a sphere, when in fact it's not?

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Most particles are often shown as spheres. In fact, it's not as inaccurate as you might think to present the electron as a sphere, since its electric field has been measured to be very close to spherical. This is explained in articles like this one which you can find on Google.

The full paper on these measurements is available on the website of Nature as well, where I have linked to here.

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Textbooks typically depict the electron as a sphere because it is a sphere, so far as it's been measured. The Nature paper @Wouter linked to is a recent measurement of the electron's shape. The lead author of that paper is Edward Hinds, who appears to be the primary person in precision measurements of the electron dipole moment. His publications page has links to other papers on this.

The most recent paper gives an upper bound of $10.5 \times 10^{-28}\mathrm{e\cdot cm}$ for the electron dipole moment. Here, $\mathrm{e}$ is the charge of the electron, so this would correspond to displacing the entire charge of the electron by $10^{-27} \mathrm{cm}$. And that's an upper bound; the measurement is consistent with the electron having no electric dipole moment at all. This is what it means for the electron to be a sphere: the electric field it gives off is perfectly spherical. (As measured. There are predictions that the electron is not perfectly spherical.)

Another way to look at it is to ask what the radius of the electron is. The best I was able to find is that the electron has a radius no bigger than $10^{-18}\mathrm{m}$. I'm sure there are better sources than that, and I'm sure there are more recent measurements, but this isn't my field. I do know that all measurements of the radius of the electron are consistent with it being a pure, mathematical point. IF you had to give a shape to a perfect point, it doesn't really make sense to call it anything other than spherical.

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