This is still not correct, and a serious shortcoming of this otherwise outstanding eBook. Electron flow is only the 'physical reality of electricitiy' in metal. Electricity can also flow in gases and liquids, where it is often made up of positive charges!
The definition of current has nothing to do with the flow of electrons, but with the flow of charge. The definition of current is:
i = dq/dt
Hence if you take the notional 'direction of current' as being the same as the electrons, then the 'q' in that equation is negative, because electrons are negative. Hence the current, i, flowing in the direction of the electrons, is negative. Simple math.
Conversely, if you take the notional 'direction of current' as being against the flow of electrons, then you have two minus signs (one for the negative electrons, one for the fact they are moving against the reference direction). Hence the current, i, flowing against the direction of the electrons, is positive. (Remember, electric current itself does not really 'flow' anywhere; it is just a scalar number, like 'speed'.)
Both situations are equivalent and equally valid. But you cannot mix the two. If you want to use 'electron current' arrows, then any current you talk about, flowing in that direction, must be called negative. Unless you intend to redefine current with the opposite sign too! i=-dq/dt (And I sure hope not, because a LOT of physics textbooks will then need rewriting!)
Since the entire world has settled on the fist definition of current, and prefers to use positive numbers where possible (i.e. 'conventional current'), then by adopting the opposite convention you are willfully making 99.9% of all other academic materials appear unintuitive to beginners. Conventional current is no more right or wrong than electron current, it is just more convenient (it's too easy to make algebraic mistakes when dealing with a lot of negative numbers). But your version of electron current being also re-defined as positive is wrong, both mathematically and historically.
EDIT: Sorry for bringing up this old thread, but the more relevent ones have been locked.
The definition of current has nothing to do with the flow of electrons, but with the flow of charge. The definition of current is:
i = dq/dt
Hence if you take the notional 'direction of current' as being the same as the electrons, then the 'q' in that equation is negative, because electrons are negative. Hence the current, i, flowing in the direction of the electrons, is negative. Simple math.
Conversely, if you take the notional 'direction of current' as being against the flow of electrons, then you have two minus signs (one for the negative electrons, one for the fact they are moving against the reference direction). Hence the current, i, flowing against the direction of the electrons, is positive. (Remember, electric current itself does not really 'flow' anywhere; it is just a scalar number, like 'speed'.)
Both situations are equivalent and equally valid. But you cannot mix the two. If you want to use 'electron current' arrows, then any current you talk about, flowing in that direction, must be called negative. Unless you intend to redefine current with the opposite sign too! i=-dq/dt (And I sure hope not, because a LOT of physics textbooks will then need rewriting!)
Since the entire world has settled on the fist definition of current, and prefers to use positive numbers where possible (i.e. 'conventional current'), then by adopting the opposite convention you are willfully making 99.9% of all other academic materials appear unintuitive to beginners. Conventional current is no more right or wrong than electron current, it is just more convenient (it's too easy to make algebraic mistakes when dealing with a lot of negative numbers). But your version of electron current being also re-defined as positive is wrong, both mathematically and historically.
EDIT: Sorry for bringing up this old thread, but the more relevent ones have been locked.