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The fact that two balls charged with 1 coulomb each would repel/attract each other from a distance of 1 metre with a force sufficient to lift the Seawise Giant would suggest me otherwise, but has anyone ever charged an object with 1 coulomb of net charge?

Why was such a ridiculously large charge chosen as the unit of charge? Or better, why did we give the Coulomb constant such a big value instead of using a value in the same order of magnitude of the Newton constant ($10^{-11}$)?

EDIT

For the historical reasons that explain why the coulomb was chosen as the unit of charge please refer to the good answers given to this question.

After a bit of research I have found that the highest voltage ever created is $32\,\mathrm{MV}$ at the Oak Ridge National Laboratory. With such a voltage the best we can do is charging a copper sphere the size of a basketball with around 424 microcoulombs:

$$Q = 32 \times 10^6\,\mathrm{V} \times 4\pi\epsilon_0 \times 0.119\,\mathrm{m} = 4.237 \times 10^{-4}\,\mathrm{C}$$

Such a sphere, when placed at a distance of $1\,\mathrm{m}$ from the surface of a similarly charged sphere, would experience a repulsion of $1052\,\mathrm{N}$ (the force needed to lift $107\,\mathrm{kg}$).

If the maximum voltage we can access is $32\,\mathrm{MV}$ and we want to charge a sphere with $1\,\mathrm{C}$, all we need is a sphere $561.7\,\mathrm{m}$ in diameter. It might often snow on the top.

moonblink
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6 Answers6

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Actually the ampere (SI unit for electric current) was defined first (in 1881, see Wikipedia: Ampere - History). They chose this size for $1$ ampere, probably because at this time such a current could be produced with a decent electrochemical battery, and was easily measurable with a galvanometer by its magnetic effect.

The natural consequence of this is: A flowing charge of $1$ coulomb (i.e. a current of $1$ ampere flowing for $1$ second) is also a convenient unit, neither ridiculously large nor ridiculously small.

The fact, that a static charge of $1$ coulomb is a really big thing, is an entirely different story, which has to do with the large electric force between charges.

Thomas Fritsch
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Has anyone charged an object with 1 coulomb?
Not a problem nowadays with supercapacitors.

Why was such a ridiculously large charge chosen as the unit of charge?
Once the second and the ampere (both reasonable units) have been chosen what else can one do.
It so happens that when dealing with electrostatics a coulomb is a large unit but that is not so in the context of current electricity.
Another example is the tesla which for most situation is a very large unit.

Farcher
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The underlying reason that 1 coulomb seems like a large amount of charge is that most charged particles in ordinary settings are nonrelativistic -- moving at speeds $v$ much less than the speed of light $c$. Compared to electrostatic forces, magnetic forces are smaller by a factor $v^2/c^2 \ll 1$.

Thus, to obtain significant magnetic forces requires large amounts of charge to make up for the slow motion. And to keep the magnetic forces from being overwhelmed by electrostatic forces, the charges must be balanced by opposite, differently moving charges -- e.g., moving electrons balanced by stationary ions in a wire.

Thus, in a coherent system of units, it is inevitable that either the magnetic effects of a unit current are very weak (as in ESU), or the electrostatic effects of an unbalanced unit charge are very strong (as in EMU and SI).

Empirically establishing the relation between electrostatic and magnetic effects of a given amount of charge is nontrivial, requiring experiments with a high "dynamic range". This can be seen because it is effectively a way of measuring the speed of light, which is at least 6 orders of magnitude away from most commonly measured phenomena.

As it happened, both the electrical experiments (effectively linking ESU and EMU) and the direct measurement of the speed of light had already been performed to sufficient precision by 1861, when Maxwell was able to compare the numbers and reach the stunning conclusion that the speed of light is an inherent property of electromagnetism.

nanoman
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The plates of "large" capacitors often receive charges exceeding 1 coulomb.

This 5V capable, 1 Farad capcator is about 5mm thick 20mm diameter and costs a few dollars Cornell-Dubilier EDC334Z5R5V

However it's not an isolated charge, one plate of the capacitor accepts a charge as the opposite charge is induced in the other plate (the plates are convoluted structures internal to the case pictured)

Jasen
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No matter what unit you choose, it's unreasonable for some purpose. For electrochemists, a coulomb is only $10^{-5}$ moles of singly-charged ions, not much. But for electrical machinery, coulombs/second (amperes) is a practical unit. The circuit breakers in your house trip at modest numbers of amperes.

These SI units are common in engineering, but there are other systems around. You might find ESU or Gaussian units more comfortable for electrostatics.

Buzz
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John Doty
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A typical tractor battery holds a charge of 120Ah = 432000C. And since the starter motor can draw something like 800A and the tractor does not start right away every time (and you need to pre-glow at lower but still non-trivial current for a minute when it's cold, when the battery does not have full capacity anyway), a Coulomb is kind of a ridiculously small charge unit.

And that's small potatoes compared to what a modern electric car throws around in charge.

What is small and large is relative.